I have the same problem looked in to wheels however all the wheels had many reviews where the wheels broke and do not hold up to regular use. This is very understandable. Adding wheels will mean you will have a longer impact zone as they will reduce your clearance by a couple inches. For me I have about a 1' scrape and the receiver seems to easily handle the scraping. I would be more incline to have a actual skid welded to each end of the receiver and let it scrape.
I read those reviews too when I started researching skid wheels for my RV.. I had the same thought as you, that they don't work and they all break. But I kept doing research on them and I learned a few things about them like, their intended purpose, different types, installations, etc.
They make different skid wheel for different RV types and applications. You have to pick the correct wheels for your situation. The purpose of the skid wheels is to give you the minimum amount of clearance so the lowest part of the RV doesn't contact the ground, scrape. There is no rule that it has to clear by a certain amount. You don't need to clear by 5 to 10 inches. As long as the RV does not scrape, you are good. The majority of us are in the more is better camp. With skid wheels the smallest wheel needed too clear is best.
What I have found out by doing my research is a lot, NOT ALL, of skid wheel failures happened because the RV owner installed the wrong skid wheel for their application.They want a lot of ground clearance so they install a wheel that is too big/tall or they install a swivel wheel that didn't swivel and it broke.
You want to keep, if not all, the majority of the weight of your RV on your axles. Skid wheels are not designed for supporting or lifting the weight of your RV. You want them to support as little weight as possible to clear. If possible you just want the skid wheels to use your suspension travel to clear while keeping the weight on the axles. This is usually not a problem with travel trailers and 5th wheels. The problem comes with class A's and especially diesel pushers. They put too much weight on the skid wheels and they brake.
Different skid wheels are designed for different applications and weight ratings. None of them are designed to carry the weight of your RV. From what I have seen a lot of the failures happen because people want or think they need a lot of ground clearance for any situation. They install big skid wheels so they can clear anything. But what happens is the skid wheels are too tall and once the suspension travel is taken up it starts to lift the RV and the weight is taken off the axles and transferred to the skid wheels and at a certain point the skid wheels fail.
Look at the pictures, I posted, of the skid wheels I installed in my RV. They are the Ultra-Fab Steel Jumbo Roller for Trailers and RVs - Weld On - 2-1/2" Wide x 3" Tall, non swivel. That is all I needed to clear the ground when backing into my storage unit.
The skid wheel just needs to be the lowest point, the bottom of my hitch only clears the ground by about an inch and my spare tire is even closer, 3/4" to 1/2". The important thing is that is clears and does not scrape anymore. My wheels have been on my RV for over 6 years and never failed. They still work perfectly and have no damage at all. Just normal wear on the rollers.
To use a phrase from the first Fast and Furious movie, with a little modification..
"It doesn't matter of you clear by a 1/2" or by a foot. Clearing is clearing".
Had to replace it. Finally modified it so there was no wing nut ,and bolt hanging down when traveling . Of course after that never got in a spot where it dragged again 
