My suggestion would be to get bubble levels and use those religiously as your guide. I have two of them on my camper, one for side to side leveling and one for front to rear leveling. Both are placed on the driver side above the front jack. The one for side to side sits under the overhang on the front wall of the camper and one for front to back is right around from that one on the side of the camper above the front left jack.
I raise and lower my camper using those two bubble levels. My RV pad on the side of my house slopes away from the foundation so I know there is probably 3 inches difference between the right and left side of the camper when it is off the truck on the pad. That does not matter, what does is that my camper is level, or even better is about 2 inches lower in the rear than the front.
If you need to get some blocks in order to raise the front end a little higher, that should not be a problem. Again, the important thing is to keep your camper level, or slightly lower in the rear.