mock up is the most important. I know a lot of guys who built tilting bed floors "for access" and with the floor tilted couldnt access anything. mock up a sheet of plywood in the position you will have the floor tilt to and see how much room you have for access. even the center split, will you be able to get to anything at the front of the bed? how often will you need to even get under there?
I had my airride and fuel tank under the bed of my 65. I was going to tilt the bed floor till I realized that there was no way to change a tire with a flat. so we tilted the whole bed. I never got to motorize it but it worked perfectly, access to all the airride, fuel system, and able to change tires.
IMG_8305 by
Joe Doh, on Flickr
IMG_8304 by
Joe Doh, on Flickr