For me a must-have was our Progressive Industries EMS hard-wired surge protection. I have no doubt it saved our appliances. We were out and about at the Black Hills for the day. When we returned I noticed that we had an error code showing the power had been shut down to our trailer. The voltage was all over the place, both way high as well as low. It turned that there was a problem in the pedestal box. Kudos to the folks at Rafter Bar J for finding the problem and getting it fixed relatively quickly.
For leveling I used a couple of the stick-on type bubble levels and 2 sets of Lynx Levelers. If the bubble level read as 1 unit away from center, I would add one row of leveling blocks on the low side, 2 units off = 2 rows, etc. Very quick and easy.