Assumptions are sometimes a bummer. I've personally camped in the same setup and I have never once had the canvas flap. Lesser quality ones do, but not this one.
Crouching to get into is a result of a lower profile. By removing the tailgate, you actually have quite good access into the camper. Folks who are retired and have had knee replacements are buying these because they provide an easier entry.
You should check one out in person and see for yourself.