Mobyduck,
I made my side guide-on's, for around ten bucks. Two inch pvc, caps, galvinizied screws, and reflective tape. Sounds home made but they look as good if not better than the ones offered in the marine stores, and the pvc is I purchased is heavier duty.
I have a bass boat that had carpeted bunks and carpeted guides. Carpet can be a pain launching a boat in shallow water, if you don't spray silicone on the carpet. Then you have to watch out on a steep ramp, the boat may take off, if your partner unhooks the winch strap to soon (almost happened to me once)!
I found a set of pvc covers in white, which matched my boat color, at a local marine store.I'll get the manufaucture name if any one is interested, these are great. They fit over the new treated two by four bunks, that I installed. This enables the boat to glide on and off easier in shallow water, and doesn't wear like the carpet.
After installing the pvc bunk covers, I removed the carpeted side guide-on's, modified the hardware so I could install two inch pvc pipe, over the brackets that held the guide-on's. I placed a cap that can be purchased for the pvc, and reflective tape. This works great, and matches the bunk covers very nicely.
This set-up doesn't marr the finish on my boat, and has been on my trailer two seasons with no problems. Best of all my trailer which is galvinizied is now completely maintance free.
Susky Kid