GG,
We've got 3 Anaconda/Spinifex stretcher beds in ours, and so far no problems (doesn't look like they will be as well). The feet on them are big enough not to put too much pressure on the floor.
Mind you we do also have a piece of shade cloth (doubled over) underneath the floor, and a massive picnic rug, so that adds a bit of cushioning as well, and lessens the chance of stones rubbing through under the feet.
LJ
PS And just in case your thinking about the bunk bed style, DONT. Assuming you have two capable functioning arms and hands, they take about 3 light years to assemble, weigh a ton, and sounds like your in a wind chime factory when you're assembling them too. Our's lives in the house for kids sleep overs...