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High Lift jacks are not meant for jacking up the rig. They are intended to be used as a recovery device. Sure you can adapt them for jacking with adapters, but do you really want to do that? They are probably the most unsafe thing that has ever been sold?
Get a bottle jack for lifting the truck...
A common fix
Run a +12 wire from RV directly to the battery on the towed rig.
Usually the lighting kit connection has only 4 pins so a 5 pin has to be utilized to accommodate the +12.