As stated above, SHOE GOO looks interesting:
https://www.walmart.ca/en/ip/shoe-goo-shoe-repair-protective-coating-295ml/6000191325754
I'd fix that door panel, before replacing it.
- even before I got nylon seat covers on my Gen3 front buckets, my Doberman Kelly had one toenail, make a small "v" puncture, on the mint fabric
- I got some Gorilla super-glue and it dries quickly
- so in 5 seconds time, I coated the foam under the seat cloth rip...with the liquid glue
- and applied finger tip pressure, for 30 seconds
- 5 minutes later, a light brushing the repair area / spot is now 100% invisible
Trex - In your case, gel and not liquid super-glue might work.
BUT:
I have some 24 hour epoxy, from my twin brothers golf club building business / I use it in many different applications.
- the slower the epoxy set, the stronger it becomes...so stay away from 5 minute epoxy, at the auto store
- mix part A and part B equally ... and apply with the tip of a small flat blade screwdriver
- do it over 2 days ... first to build up and get some under the vinyl, eliminate pockets / strengthen the bond, from inside-out first
- plus tape glue repair with masking tape on vinyl, while glue is drying underneath / this will de-stretch the vinyl & keep area flat
- next day, lighter coat of epoxy & allow glue flow to feather out level
- the look of the job, should be decent enough...got to control the screw driver tip like a small paint brush...and dab it in
- less mix is better, to start...don't overload slotted tip with glue, to control product / for the very best repair look
PS - tape the crack off, with masking tape...leaving 1/16" of undamaged vinyl exposed.
- a cue-tip wetted in Acetone, is a great little tool, to remove excess epoxy / and the edge of a wooden Popsicle stick, is good for final leveling out glue
- to me the repair, could be very successful...just take your time and carefully apply the leveling agent / paint repair area with matching model paint enamel