Thanks all. Makes me feel a lot better.
If I am lurching or fall out of bed, I will worry about leveling! And it sounds like the plastic blocks work well and are easy to carry. I think if the site is so unlevel that one or more wheels is off the ground, I will find another site--sounds dangerous, frankly.
Now, considering I have problems with vertigo, especially at high elevations, I will need to bring an actual level with me, because I won't know if my lurching and falling out of bed is due to an unlevel site or just being dizzy! (I once made a serious mistake of bending down to pick something off the floor on Pikes Peak and ended up staggering for two days. I looked like a drunk lady, but luckily my vertigo never bothers my driving, just walking.)
Interesting that a couple of motorhomes I saw with two slides on the same side came standard with automatic levelers. They said it was due to so much weight on one side when both slides were out! Sort of like everyone on a boat standing on one side???