-- Last Updated: Feb-28-13 4:00 PM EST --
... before posting, and wouldn't have suggested this model if it didn't seem to fit the bill. At a slope of five feet in ten, that means almost the first two feet at the front are within the OP's height specs, and I don't imagine sitting at one end of the cot, if it's perpendicular to the front door, would be any less convenient than sitting at some other part, since any other tent that's tall enough would probably have a limited zone having full height too. Put the cot cross-wise to the door in the two-person model and there'd be more than enough ceiling height along one entire edge of the cot. Also, considering the amount of sag in a cot where one's butt is planted, only an NBA player would actually need the full three feet of cot-to-ceiling clearance specified by the OP, so again I figured the trailing edge of ceiling height in that front two feet of the tent would be "close enough", height-wise. Not a perfect tent for everyone for various reasons, but one I thought worth mentioning based on the OP's specs alone. You suggested a regular campfire tent, and considering that a cot user probably doesn't care about weight, that's certainly an even better option.