72 long fleet bedside question

[Mike_The_Grad]

I have to do some repair work to my long fleet bedside where I tried to weld close the dealership installed aux. Fuel filler door for the aux tank that used to exist under the bed. I tried to patch it years ago but ended up making it worse by using too thick gauge sheet metal for the patch. Turns out the bedsides have curves and are not perfectly flat like my patch piece was. anyways, I have a donor door shell that I been picking apart and harvesting metal from for other repairs but the outer door skin is cherry. No rust,no dimples, no holes. I was looking at the profile shape of the door skin and looks to be pretty close to the same shape and profile of the bedside in front of the wheel arch area. Suppose I use the outer door skin as a patch panel for the bedside? Any thoughts? I understand its quite a bit of surface area to tack weld with my wire feeder. But I've already honed my skills on all the cab rust repair I've done the past 2 years: outer roof skin, cab corners, inner/outer rockers, floor pan pieces, kick panels, heck even around back window and windshield pinch weld areas where i had to get crafty and make my own patch pieces, also outer door skin corner patches. Ive got my welder settings dialed for sheet metal on these trucks. I am pretty sure I want to minimalist welding on and crowned surfaces or at least split it diagonally rather straight across the ridges or body lines. Any other tips or input? I did measure the usable area of the door skin compared to the wonky bedside area and I can make it work. Its just a lot of metal to tack weld. Compared to a full bedside replacement unless I found good straight original bedsides for a reasonable price locally.