Can I stick ceramic (floor) tiles directly onto plywood or OSB? I'm a
little tight for clearance on a potential project (at least if I use 3/4"
for the subfloor, and I worry that anything less will flex too much and
crack the tiles*) so it'd be nice not to have to use backerboard if I
don't have to.

* same with the underlying frame; I'd rather use 2x6" than 2x4" even
though the latter would give me lots more height to work with.

cheers

Jules