I am going to tackle something similar on my willys in a few spots ...
if its extensive damage then for your yj there are steel replacement
pieces available at classic enterprises including (I believe) all the underfoot
panels for yj wrangler/cj type tubs ...
see
http://www.classicent.com/jeep.phpyou'll notice body panels have dimpels/creases formed in them as opposed to just a flat piece of
steel , this increases its strength by something like x2 so it wont feel spongy like you'll fall thru
Fred Flinstone style ...
something to consider as having someone make large pieces form correctly can be time consuming
and you may find you spent as much $ in labour ...
if going with the classic enterprises route then let me know maybe we can split some shipping costs
as I may need a few things shortly ...
having said all that ... if you just need a patch or two or cheapest is best forget everything I said