Using Heated Seed Trays with Humidity Domes to Grow Outdoors?

I don't really have land and won't for a while. Right now I'm trying to come up with a highly portable system to start warm season vegetables in early spring.

There's not enough light indoors where I am and I don't want to invest in grow lights. My idea is to use seed trays and humidity domes (as pictured above) with heat mats to grow the seedlings outdoors. I'd take them inside during the coldest nights (<24F or so) and could use cheap thermometers to keep an eye on interior temps. I figure the heat mats would keep the plants warm and healthy until transplanting time.

Has anyone tried this? Any reasons why it wouldn't work? Any better options? I've searched around but haven't found any helpful info.

heat mats are usually used for sprouting only, once the sprouts are growing the mats are removed.

I see no problems with using heat mats for when you bring them indoors at night, but you can cook the baby roots if you have them out in the sun with a heat mat underneath that is turned on.

The tray in your picture is a decent one, the black bottom is designed to grab heat from the sun as well as provide a dark environment for the roots.

High humidity, like would be created by growing the plants under a humidity dome can lead to rotting and fermenting. I typically remove humidity domes as soon as the seeds have germinated. If sunlight shines onto a humidity dome, it can quickly create temperatures hot enough to cook seedlings. So for me, humidity domes are for germinating things indoors, but not for use in sunlit areas or after seedlings have germinated.

I grow plenty of things in similar seed trays.

Got it; heating mats and humidity domes are just for starting seeds. I guess I'll just make temporary cold frames out of hay bales and plastic then.

Check out winter sowing.
http://www.wintersown.org