I've tried them all - Lego bricks, solid steps and curved leveling boards. Everyone has their own problems. Lego bricks are very difficult to put together, they fall apart if you lug them around a bit and load/weight them with an RV, it's easy to rip the end off solid aligners, and curved aligners are a bit of a safety issue I think you put something on the other side of the wheel. Keep your foot on the brake before it rolls back. Bent aligners can also interfere with the wheel well. All of this requires a driver and a spotter. After spending about 30 minutes assembling 2 sets of Hopkins I can ride them myself, they don't flex or flex at all, they don't interfere with the fender. or wheels, and there really aren't any safety issues or anything that could break. The only downside is that they offer more storage space than others (and are heavy if you're using treated wood). I prefer plain and bulletproof ones. To me, Hopkins is simple and bulletproof.