Welcome to JOF. Not sure how handy you are, but I'd probably fabricate something myself. Might take a little trial and error. Could laminate your own door using FRP from lowes for inner and outer skin, foam or wood core, or both, might use some thin aluminum angle to trim it out. Lots of possibilities. Got any pictures of what you need?
Then again, now that I reread the post, was it a plastic door?
John and Rebecca Dickson
Emma-13 / Little John-10 / Iva-7
2013 Ford F-350 Lariat FX4, CC LB PSD, DRW
2015 Jayco Jay Flight 28BHBE (#8)