I had my "Pendaliner" liner out & Swiss topper off all summer and before reinstalling I wanted to have warmer cap & bed this winter, so, I insulated part of it today.

I bought the $32 4'x25' silvered mylar bubble-wrap from Homies dept - 5/16" thick insulation w/ R-4 performance. I also got the extra-gnarly butyl rubber outdoor duct tape.

I cut the 1st sheet draped from rail to rail and conforming to front end of bed, including all the dimples and left 3 inches above rail to tuck in crossbrace bracket, cut V-darts to accomodate the sheetmetal's bends and then tacked it in place with looped (double-sided) gnarly duct-tape. The flats between brace brackets were trimmed off 1/4" below sheetmetal seam on inner rail.

I cut two 4' pieces 31" long to catch the rest, it took 8' 3" to drape from rail to rail, etc. and covered front wall with a 17" 4-foot chunk and scraps then taped it all with normal foil-backed duct tape.

I added foam gasket under inner bed rail molding & silver taped sheet metal seam - those breath straight through and are a bigger air leak then the tailgate..

The Pendaliner slipped right in and still has NO interferance fits with any of the rails or tailgate, etc - and all the tiedowns installed w/o moving plastic - I am impressed I could add 5/8" and not have liner pop up or interfere with rails!

Now the hard part will be insulating the white fiberglass interior of the topper >: (

EDIT - Signature pix not showing up