I believe lack of an OEM Spare and an OEM Jack play into the seller's hands two ways: 1. Cost and 2. Liability. Seems OK to furnish a one-size lug wrench, which is actually pretty doggone beneficial. But get a piece of pipe to slip over it. You may be able to achieve 140# on an E-Series Ford but you may need much more to break lugs loose that have been tightened with an air tool. Again, I would not choose a bottle jack less than about 8 tons. I have 4, 6, 10 (bought to carry in the RV) and 12-ton hydraulic bottle jacks. The 4 and the 6 WILL lift one end of the rear axle, but it's too hard to gain enough leverage under there. The 10 is OK, and the 12 is effortless. I think it could be because the 10 is Harbor Freight and the 12 is a genuine old American-Made Blackhawk.
You can argue for changing the flat supported only on a jack because you won't be under the coach, working from beside instead. I believe we could still be easily injured so I have a jackstand and plywood to put under jack and jackstand. Even if you feel OK with no jackstand, I'll ask this: IF it DOES pop off the jack, and no jackstand, HOW will you get it back under there to pick it back up, what with no wheel in place to allow some room?