At the risk of being shot down in flames I would suggest it’s a good idea
I wish I’d thought of it
I estimate it will give another 720mm in length which might make the difference of the rear barn doors closing
As you say, it would only be for a few lengths of small diameter pipe, for me it would be lengths of small section timber
I’m no structural engineer but I don’t think cutting the thin tin work would weaken the seat
You could cut two holes either side of the beefed up vertical tubular support
A new piece of tin could be fitted when not in use, held on by magnets?
I might give it a try this weekend
If like me you have very little roof clearance when reversing into the garage you could try lowering the rear springs
I used Midland Road Leaf Springs 01675467387
info@leafsprings.co.uk they’re based outskirts of Birmingham, you take the van to them, they remove/modify/refit your own springs while you wait
They do a deal for members of this forum and I found them very reasonable priced and efficient
If you search my previous posts you’ll see more information about them