My first TT, a Dutchmen Sport (see my profile page) had an outside access door for under the dinette. I really missed that with our second TT, our Springdale, which did not have an access door. My 3rd TT has a stand alone table and chairs (now removed completely).
I've seen inside access doors under dinette seats on several models and a few access door for the outside too.
It would be a fairly easy modification to do if you had the door. If doing it, get the door first, then you know exactly what you are measuring against to cut the hole.
Good luck!