And I thought I was the only class A owner small enough to get under the coach without lifting it. As long as there's enough clearance between the lower A arm and the ground to get the drill in place for step #2 of the instructions and get the bag in place you should be OK. Once the bag is in it should be good to inflate without the need to lift the front but just to be sure first fill them with a few pounds of air to see how well they are expanding within the spring before going to full recommended pressure
If not Northern Tools sells a very good 12 ton jack and matching jack stands for less than $100. Before I installed hydraulic levelers I used them to level at camp sites if we were staying someplace more than a weekend. 12 ton might be a bit of over kill but it makes for a good safety margin.
