I should think a light frame should be enough to keep them off the exhausts on your bike. The weight is on the saddle straps and a frame maybe just to keep them away from the exhaust.

On mine I just make sure that the bags are quite high up and so are protected by the standard plastic heat shields on the standard exhausts.

So when you view from behind the bottoms of the bags stick out a bit more than the top, like the letter A and not flat sided like the letter H if you see what I mean !