I kinda like the idea but it seems to me bugs would get to be an issue. I also can't see staying dry on a dirt floor in a good rain. Back when these were in common use they would dig a trench around the tent to funnel water away. Obviously that isn't kosher anymore so I think, unless you get an absolutely perfect spot or you have some sort of an in with God to be certain it won't rain on you trip, you're going to get wet.
But then again, I'm saying this as someone who's never used one of these tents. Closest I've come is an old wall tent we stayed in at Boy Scout camp as a kid. Lots of water flowed under those tents but we slept on cots so as long as we kept our gear off the ground we were ok.