Caulking a large gap?? (pictures)

Any way you can get a carpenters flat bar worked through the crack to get on the inside of the hole? You could then take a ball hammer and lightly hammer flat or with the ball end, rub flat the damage. You could then get some 1/2" x 1/2" aluminum at the hardware store, drill some holes through the angle and RV metal skin, embed the angle in QUAD caulk or similar, and rivet the pieces together. It looks like you can also rivet to the lip of aluminum where the skin meets. Rivet to that too then trim off the excess if any with a 4" grinder. Use 1/8" x 1/4" stainless steel rivets to fasten.

Not sure if this will work for you but it's an idea.
If it won't, try Eterna Bond tape. Supposed to be pretty tough stuff.