Tents this large are usually kept in place by balance tension on multiple tiedowns on all four sides. Stresses on a tent this large are quite different than on a RV awning. I think you will likely have a few more tent manufacturers telling you they don't make a tent to fasten along one edge to a RV.
For this kind of space we used military surplus tents, usually a couple hours to put up or take down with a crew of 6-10 men. Those were heavy and meant for long-term use, but they were cheap as surplus in the 1950s. Tent rental companies have lighter "easy up" tents for short term use, but they are still tied to the ground all around when they are that large and intended to house masses of people.