I had the same crack about 2 to 3 inches long near the door lever. I pop riveted a mild steel patch (thin) on the back of the panel to reinforce the crack (lightly countersunk the rivet heads) then I sanded all the plastic above the seam on the panel.
I took a piece of naugahyde material the length of the panel plus several inches and folded the edge (about 1/8' fold on the work bench) using contact cement. I let it bond and dry. This folded edge I started bonding into the door panel groove that cuts thru the door lever. I started doing about an inch at a time working my way up the panel. I left the hole for the lever till last including not cementing the area around the hole. After the cement set I sliced the fabric so it could be stretched and cemented thru the opening. I also cemented and stretched the fabric over the top and to the back of the panel. You have to remove the staples for the window wipe and install the wipe over the fabric. I saved the staples and reused them.
It sounds like a lot but it went pretty easy and considering what those freaking panels cost, it was worth it.
I took a piece of naugahyde material the length of the panel plus several inches and folded the edge (about 1/8' fold on the work bench) using contact cement. I let it bond and dry. This folded edge I started bonding into the door panel groove that cuts thru the door lever. I started doing about an inch at a time working my way up the panel. I left the hole for the lever till last including not cementing the area around the hole. After the cement set I sliced the fabric so it could be stretched and cemented thru the opening. I also cemented and stretched the fabric over the top and to the back of the panel. You have to remove the staples for the window wipe and install the wipe over the fabric. I saved the staples and reused them.
It sounds like a lot but it went pretty easy and considering what those freaking panels cost, it was worth it.