Need help with my bed

Okay so I'm currently building an 86 toyota pick-up. I bought the truck with a pretty beat up bed, but I have cut all the rust out and made panels welded them in, anyhow I the outside of the bed is done and blocked. But i have the bed cut for 20s and the center section for xmember. The clean look that I like is to sheet the inside with tubes and maybe a removable center section to get access to the bags. But here is my problem. If I start to weld up sheet metal to the inside of the bed I"m afraid it will affect the body work on the outside, getting hot and cold, also what would I do about the seams, would it be safe to fill with body filler? someone said something about seam sealer, I've never messed with that anyone have any info on this? maybe someone has an artical write up on doing the inside of the bed. I would like to get an idea of the procedure of this as I'm trying to go about all the right ways on this truck.... thanks in advance.

Miller

When I was doing mine,I started out with welding the bed sides sold,but if any body damage in the future ,can't be repaired. Made all new panels removable. all seams inside & out where wielded up, then coated with a rust preventer & sealed with seam sealer( get @ paint supply store), then epoxy primer!
Hope this is some help,if photo's needed, can send to you!!

when i done mine i used some stuff called panel bond (its some good shit)on the tubs on the notch cover i used seam sealer then i used an epoxy primer

truck action, you said you welded up all the seams but made it removable? Also the pictures you have would be of great intrest. I'm not to worried about future body work because if this bed is damaged in the future it's not worth fixing... one time on this bed was enough. my email is