Is there any plumbing, wiring, framing, wheel humps or other oddity behind the new cabinet?
RV cabinetry isn't the same as regular cabinetry, I found out the hard way. Sometimes it's bolted to the wall frame from the outside before the outer skin is put on making it extremely hard to remove. Can you install the lift without removing the cabinet? With all those small drawers and doors you may need to find a way to disassemble the lift and reassemble it inside the cabinet, or it may fit straight down through the slot you cut in the top. Double check!
You'll need to rewire the power to the underside of the cabinet. Do you have a spare space in your circuit breaker box? It's may be easier to run a whole new line than trying to open up the walls to re-route an existing circuit. You'll need enough power to run the lift, the TV and any DVD player. A 15A circuit should be fine.
Any sources will need signal wiring as well (DVD, antenna/cable). If you relocate them to the new cabinet that's pretty easy if you leave them in the old cabinet you need to find a way to run cable under the floor to the new TV location.
It's not rocket science but I'd say you're in for a whole weekend to do a decent job.