I have the slider on my Curt and it provides more than enough tailgate clearence and turning radius, it's a must for the SB trucks.
I have used the leveling system a few times without issues. I'm just doing it like my dealer instructed and it has worked fine. I lower the front jack extensions at about halfway and then extend the jacks. Once the truck is gone I lower the jack extensions on the middle and rear as close to the ground as possible and still be able lock them. Then hit auto and wait for it to finish. Unless you're on a super unlevel spot OR I'm just missing something, I don't see the need for blocks under any of the jacks. My middle and rear jack extensions will hit the ground before the jacks even start extending. I set the extensions about an 1"-2" off the ground and let it do it's thing.
One thing to watch for in the main bathroom is the tailpipe pipe going from the sink to the P-Trap on the main drain pipe under the sinks, mine cracked in the sinks. Not the sink - the plastic flange. When mine was plumbed the fittings where the tailpipes connect to the P-Traps were off about 1/2" which put everything in a bind. Which in turn caused the plastic flanges in the sinks to crack. To fix it I bought new flanges, took the main drain pipe under the sink out and cut 1" out of the middle. This will allowed enough movement in the main pipe to be able to properly align everything. I installed a premade rubber coupling hose with hose clamps at the cut, reinstalled everything, aligned everything and tighten it all. That took care of the problem.
Hope this helps.
2015 Pinnacle 36FBTS
2015 F250 SD Platinum 4x4 - 6.7L PSD :
Titan 50 Gal. Fuel Tank
Slotted and Dimpled Brake Rotors
Air Lift LoadLifter 5000 Ultimate Airbags with WirelessAIR Controller