I replaced the awning rails with gutters two summers back on my 06 Hurricane 31D. Easy job. took a day each side. I also replaced all the putty tape under the roof material and installed the gutters using stainless steel hardware along with sealant on the threads. Seal both the top and bottom to ensure water never gets behind the rails. Added basic RV extension at both ends.
The problem your going to run up against is finding a supplier. The gutters come in 16' lengths which will require freight shipping ($$$). Another problem was some supply houses will only sell a minimum quantity which is usually enough to do several rigs. I found a local small RV service center that had no minimum order and their supplier cut them in half (8' lengths) and shipped via standard ground rates. I had to order in 16 foot lengths which worked out fine with a bit of waste for a 31' coach. Continues length like a house would have been nice but they still work. Butt the two ends against each other and a dab of sealant to water proof.
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Freedom RV Rentals | VA RV Dealers | Virginia RV Dealership and RV Rentals) Freedom RV, 11256 Old Telegraph Road Ashland, VA 23005 804-798-3379, is where I found them. Cost me about $94.67 for 64 feet of gutter. With basic extension no more black strains on the coach. Sorry but no images of the coach where you can see the gutters. Best upgrade for the cost.
Also when I level my coach I try and set the driver's side front corner low to drain the AC's that direction if possible.