Karebear. Look at my profile, it has pictures. I have BAL Quick to Ground manual jacks on the front only. I have a bubble level on the drivers door and one on the dash. As I pull into each site I try to get as level as possible using the bubbles on the levels. I find that I can get darn close 90% of the time and don't need any other form of level blocks. My unit has a Mor-ryde suspension in the rear and I have it set up so the front is slightly lower than the rear. This usually causes any levelling needed to be at the front where the jacks are and I can crank them up as needed in just a few minutes. Saves weight and also expense. Mine came from Camping World and were about $500 installed as I recall. They make them for the Ford as well.
You might want to click on my name and read my back posts. I have added quite a few comments about the 251 and Trail-lite.