The install time will take the better part of a day. But it really depends on the condition of things like bolts, skid plate, etc. I took the time to sand and paint the rear crossmember as it was pitted.
Make sure you get a backing plate to mount to that on the inside of the crossmember. You can get one from EE. Also make sure your tank is as empty as you can make it. Don't try siphoning, their is a flap in the tank entrance that prevents getting a siphon to the bottom.
The install conceptually is straight forward. Disconnect your rear swaybar. Undo the various bolts for the rear bumper and remove. Stick a jack under the skid plate assembly to support the weight of skid plate and tank. Undo the skid plate bolts. Drop the tank. Make sure you only drop the tank about 6+ inches (the rear wiring harness does not give you much flexibility, neither does the tank fume handler in the passenger side wheel well). In addition, you can push the tank slightly forward to gain access (up to the ball joint assembly). You'll need to place the backing plate and nuts/lock washers/washers on sight unseen. It's not easy, but not impossible. Once done, reverse the order of disassembly.
If you do go with a backing plate. You'll need longer bolts that those supplied with the kit. I don't remember what I used. But get an assortment of lengths. Just return the unused ones. You want to make sure the bolts do not stick out past the rear crossmember. Otherwise they will spear the gas tank.