Preserving sweet potatoes in hot & humid NE Texas?

Help, please--  I'm a permie newbie, and grew some nice sweet potatoes this year.  The two test potatoes I dug out cured nicely in the hot, humid garage in late Sept - early Oct, but they also apparently decided that Dallas is in the tropics and promptly sprouted slips. I live in a flat ranch-style house, cement foundation that heats up to around 72 degrees Fahrenheit in the center of the house by August, so there are no "cool, dry closets" here for storing sweet potatoes.  Additionally, the water table is about 3-5 feet down, making a root cellar impossible to dig.

So, my question- how do I dig, cure, and store useable sweet potatoes in this weird climate?  I can't dig them right when I need them, since they must cure, but I have no cool, dry place to keep them if I do dig and cure the lot.  Anybody else have this problem, and how might I overcome it?  Many thanks in advance...   ::

Tough problem. Are you sure about the water table?

You know what I do when I'm not ready to harvest everything? I leave it in the ground and harvest as needed. Mulch with straw or leaves to keep it cooler. If I don't get to it all then I just get more potatoes. Of course it's not quite that simple but I have many perrenial annuals this way

Another alternative is the old style of storing in straw in a mound, so a bit like an above-ground cellar. I really don't know the specifics but my great grandmother had a structure with a roof specifically for this. Anybody know what I mean or have one?

Trish,
In the ground the sweet potatoes stain and rot, so harvest them.
Curing should happen at 85 degrees Fahrenheit and 85 to 90 relative humidity.

Storage should be 55 to 60 F, so it does not need to that cool. Within a couple weeks of harvest they should be brought down to the storage temp otherwise high temperatures result in excessive sprouting.   Relative humidity needs to be high too, 85 to 90 percent.

Light and high temps cause sprouting.  The sweet potatoes are also respiring, so there needs to be ventilation or the CO2 will kill them.

Here is a good reference link:

http://commodities.caes.uga.edu/fruits/veg/pubs/documents/sweetpotato.pdf

So this might not make a lot of sense, but do you have any space around the area that your main water pipe comes into the house?  I'm thinking kind of along the lines of the old spring houses people used to use as natural refrigeration.  I don't know if it would make any difference at all in a hot climate, but the area around where the ground-temperature water comes in might be a cooler microclimate.  If you could add some insulation around the space to keep that cooler air in, maybe it would be just enough to offset the worst of the heat?

Also grasping at straws: maybe an evaporative cooler/ zeer (example: http://www.offthegridnews.com/grid-threats/evaporative-coolers-how-to-build-your-own-off-the-grid-refrigerator/ )would work for storage.  I have zero practical experience with them and I don't know the particulars of your climate, so I really don't know how effective it would be overall.  Basically, I'm thinking you could use water in some way to create a cooler space to store them, but past that, I got nothin'.

I can't find sources now, but my reading on storing sweet potatoes (once they are cured) has pointed out that they store well (not optimally, but well) at room temperature in a climate-controlled home.  The classic advice is to keep them in a milk crate under your bed; if you're happy, they will be too.

The summer garage sounds like it was close to OK for curing.  And your indoor conditions aren't quite as cool or as humid as would be optimal for storage, but they don't miss it by a lot.  In milk crates on the floor of the laundry room might not miss it by much.  

I have had pretty good luck just keeping them on the floor indoors.  They don't keep all winter, but they do keep for several months.  And they don't rot; eventually, they get lesions on the skin and start to sprout.  Once they've sprouted too much they are woody and unpalatable inside.

Thank you all *very* much for your help-  in addition to all your good advice, a librarian at Tuskegee University Library found me the early 20th-century bulletins issued by Dr. George Washington Carver.  Dr. Carver conducted his sweet potato experiments at the original Tuskegee Agricultural Station, which happens to be in Alabama on the same zone that I'm in, currently ranked as 8a, and experienced a lot of the same weather patterns as Dallas does now.  He includes clamps (conical structures Eric Bee recommended), and also notes that cured sweet potatoes last 9+ months in good condition while stored in a room that varied in temperature from the 20's Fahrenheit to the 90's Fahrenheit.  Wow.  So if I cure them well, hopefully they can live happily pretty much anywhere in the house.  He also notes that 2-year-old sweet potatoes that are sprouting may still be edible.  Here's the Library's link, as well as a few others that I've found:

Tuskegee Library collection:
http://192.203.127.197/archive/discover?scope=%2F&query=carver+bulletins&submit=

Cross-reference for bulletin titles for bundled posts following:
http://www.tuskegee.edu/about_us/legacy_of_fame/george_w_carver/carver_bulletins.aspx

Amazing collection of bulletins as well as other pamphlets:
https://openlibrary.org/authors/OL826136A/George_Washington_Carver

UC Davis bundle of bulletins 1905 - 1916 (I include these since they don't have the distracting Tuskegee watermark on the pages):
https://catalog.hathitrust.org/Record/008521316

Weather records kept by Dr. Carver:
http://www.lib.noaa.gov/collections/imgdocmaps/tuskegee.html