A product called Bugs B Gone found at some auto parts stores (just bought a concentrate at Lordco in Canada) works great for me. To help out I regularly apply a protective quick wax from Thetford that just wipes on with minimal elbow grease. Cleaning with 20/20 windshield wash and the Bugs B Gone and rinsing and drying well first is necessary.
I tried Aerospace 303 once this summer, but the bugs didn't clean off as easily the next time as they did with the Thetford product on the surface. The 303 is best for UV protection, but doesn't seem as slick.
I'm not sure I'd use very hot water; it conceivably would soften and remove any protective wax you've put on, plus it might soften the film enough that scrubbing could then leave micro scratches. Such scratches give the next batch of bugs a better grip, making them that much harder to remove.
Joel
Currently entertaining similar Montana bugs at Jim and Mary's RV, Missoula