NEED QUICK! Easy Outdoor Composters for 300+ Wedding in the Ark Ouachitas (rocky, clay)

How do I make composters for a 300+ peep weekend wedding on a creek in the Ouachita Mountains?
On a budget? Wedding in 67 days!

I have lived with a biolet and outhouses...but, stuck on design ideas for a mass amt of folks.
Mill is down the road...so sawdust is easy.
We may have access to a backhoe, and could def use the compost for the 2013 garden.
Any advice would be greatly appreciated!
I am in a 'back n forth' with my Dad, and just want to prove that pooping with a breeze is so much nicer than blue chemicals stuck in a plastic box!
Most of the guests will appreciate composters as well.

Thanks!

Free 5 gallon buckets from ??

We set up a sawdust bucketsystem in addition to our outhouse and house sawdust buckets for a wedding of one hundred but just for one day. We were ready with several primed buckets and lots of extra sawdust and someone to check periodically to make sure folks were covering their deposits and that we had enough tp. We also had a set up for washing hands and towels. Ours was tarped (a nice generous space with a changing "room") and set back on a path in the woods so I think did not get thoroughly tested as some just grabbed a little tp and went off into the trees to pee. We just balanced the toilet ring and lid on the bucket but if you have lots of boards you could make a nice stand.
In my opinion, Port o potties/chemical toilets are GROSS!
Did you mean you could dig a hole when you mentioned a backhoe? That could be the easy solution...with plenty of sawdust...no smell no maintenance..but not near a creek...is it on your land or in the National Forest? a camp out or two days daytime?
Someone in another thread mentioned using strawbales to form the hole with board lid.