First off fiberglass fenders may need to be heated a little with a hair dryer, or similar, to get them to fit good. It all depends on how they were stored when "green".
While I have heard a bad tale or two concerning R&R Fiberglass out of Tennessee I've used Richards fenders and running boards on several vehicles and have not had any problems. I also have some on my 37 that have been on it for 15 years and never no cracks or "stars" in them. I didn't even use the fender braces (didn't want to drill holes in fenders) and they are holding up fine. R&R laps their fiberglass, not sprayed. He has been in business for many years so I do recommend giving them a call. Tell him your a Stovebolter and don't be afraid to ask for a discount or help on shipping.
Oh, and my running boards are holding up fine.