Welcome to the forum. I think your posting should be OK here, but Roger [Randa] may move it later if he thinks best.
Unfortunately your gas locker door is not going to be a cheap fix. If you are very competent then you may be able to drill out the rivets around the edge and strip the door down. Then you would somehow have to take the ribbed outer skin off and source/cut a replacement panel before fixing and rebuilding the door. If you decided on a replacement I believe £1,200 has been quoted by Eriba dealers.
With these figures or level of work in mind I think unless you can 100% solve the problems of your bikes damaging the panel again, I'd be leaving it with the dents in.
Colin