It's called a "pinch flat", and it happens all the time in the Mt Biking world (and why I ride tubeless nowadays).
Caused when a good amount of pressure pinches and pops the inflated item, while not puncturing the tire (or in this case the tent floor). This flat always looks like a tear, because it is, and is really hard to patch even on a tire.
If you want to use a inflatable at 255 lbs, I am sure you could but I would just avoid the ultralight models (use models like neoair all season, TAR Prolites, Exped Downmats, etc.). All of these models have much tougher exteriors, and there are many that cowboy camp on them with zero issues.
The nts of restful sleep on an air pad would offset the horrible CCF nights IMO!