I guess I do not quite understand your question. I take it to mean that a TC meant for a short bed (but has permanent mounted rear wings) you want to remove them such that it can be pushed forward for use on a long bed???
If I understand you correctly, I was considering it for my situation. The Northstar Arrow 8' camper comes in 3 possible configurations from the factory:
1) long bed version with just a flat panel in the back
2) long bed model (same as above) but with "bolt-on" skirts for a short bed (removable for a long bed.)
3) short bed model with permanent skirt storage wings.
All 3 are essentially the same model and I have the short bed version on a long bed truck... it was such a great deal that I could not pass up and my first thought was to cut off the permanent skirt wings, but I would have had to find another location for the batteries as they are located there in this particular version. The reworking of it would have taken quite a bit of effort to look good and not like a total hack job.
I had to travel a few hundred mile to purchase the TC and I rigged a support to keep it in place for the trip so that it would not scoot forward in the bed. The camper skits wings would have hit the truck tail light in a sudden panic stop situation without any blocking between cab and camper.
I still considered chopping it once I got it home, but that extra storage space kept telling me no... it is so welcomed now for my generator and has been this way for 6 years now.
I have posted mine many times, but here is one that I was having some fun with Photoshop... If I removed the wings, then it would just scoot forward similar to the long bed factory model. The way I have it now is very similar to your Mega cab set-up... only my "stage space" is not filled up with truck cab of the Mega.
Sold the TC, previous owner of 2 NorthStar pop-ups & 2 Northstar Arrows...still have the truck:
2005 Dodge 3500 SRW, Qcab long bed, NV-6500, diesel, 4WD, Helwig, 9000XL,
Nitto 285/70/17 Terra Grapplers, Honda eu3000Is, custom overload spring perch spacers.