Parallel 4 link rear coil spring suspension w/ Long Travel IFS

Hey y'all!

I will be getting a second, or third generation Tacoma in the coming year. I am planning to run a Parallel Rear 4 link set up. Attached below, are pictures from Shaffers off road of the identical rear setup that I am talking about

For the front suspension, I am just going to put in a Long Travel IFS kit to compensate for the lift I will be getting in the back and run 33-35 inch General Grabber tires. In addition to all that plus front and rear ARB Air Lockers, I also plan to have a flatbed and shorten the frame around 20 inches behind the rear axles once it is all linked up to work better off road. The only problem with coilovers is that I am not able to create a true flatbed. Thus if I go for a 4 link parallel coil spring rear suspension w/ shocks, then I can keep all of my suspension parts at or below the frame. In other words, the suspension will not go through the bed area.

What I plan to get out of this build is that I am looking at an all purpose rig that can be a daily driver, haul items in the bed (thus looking at coil spring w/ shock set up to retain all of the bed space), expedition, and rock crawling as well. This will not be used for high speed, pre-runner type off roading.

My question is, how much time will it take to build all that, and would the cost be around 30k for all of this? Lastly, would it be wise to buy a 2015, or 2016 Taco 4WD, and then do all of the aforementioned planned fabrication work?