I presume you are talking about what support is needed in the truck bed under the camper to clear the bed rails ?
Attached find a picture of how I do it....the longer sticks were initially used to see if I needed more material to clear the bed rails...once I established that I just rely on the shorter 2x4's with plywood caps running across the bed and pulled the longer sticks out completely before loading the camper. If you have a 10' cabover you will need additional support under the camper door and on top of the opened tailgate.
popRoid, what are plywood caps and how do you keep you 2x4s from sliding? Thanks, Joe
More pictures attached which explain everything:
I use a total of 7 of these supports ....2x4 with 1/2 inch plywood caps attached to each. This will accomplish 3 things: 1) supports the bottom of the camper in the bed 2) raises the camper up enough to clear the bed rails of a 2017 F350 aluminum bed (other trucks might need more or less clearance) 3) gets the bottom of the camper above some standing water in the bed. If you have a 10' cabover on an 8 ft bed you will need one support on the rear dropped tailgate under the back camper door for a total of 7 supports.....6 in the bed and one on the dropped tailgate.
My F350 has a sprayed Rhino bed liner and with the Alaskan I had Brian Wheat add additional insulation to the inside floor.
The 2x4's are of several lengths depending on where they are placed inside the bed and up against the wheel wells. I use a separate 1/2 inch piece of plywood up against the rear wall to keep the camper from rubbing (see in picture)..
NONE of the 2x4's are bolted to the actual bed of the truck and all just "float" independently under the camper. I also have never used a rubber "horse mat" as have not found it necessary....the tie downs will keep the camper from moving much. I've travelled over 20,000 miles using this system with no issues. This method is how the Alaskan factory in Winlock did it when I picked the camper up.
NOTE: if you are storing the camper (off the truck) I use a set of camper packers from: https://www.torklift...v/camper-packer
and the Reico Titans are all mounted as well on the camper for backup to the camper packer.
Happy to help....If you need anything else just post away.