Modifying Dometic Air Distribution Box to match 1975 Argosy curved ceiling

[Atx2001]

1975 Argosy 28ft

I've found that when I hold my new Dometic manual control air distribution box for my Penguin II up to the ceiling, the curve keeps it from mounting flush. My instinct is to trim away at the plastic with my Dremel or hacksaw until I can achieve a flush mount.

Before I start cutting though, is there anyone with experience in this situation?
I'd be grateful to hear how others have solved this problem. How were the results?

Thank you DIYers!

[AlinCal]

I mounted our new Penguin yesterday and no ill effect with the fit of the D box.
It gets screwed around it's perimeter anyway.
What I Don't like so much is the condensate kit and its added 1" foam gasket material thus raising the entire unit off the roof that much more than the standard 3/4" gasket.
I wish Airstream would have kept the contoured base(now discontinued) that was original(mine was toast) but my guess is the newer trailers have a flatter roof profile and it's not needed?

[Burnside Bob]

Originally Posted by AlinCal

I mounted our new Penguin yesterday and no ill effect with the fit of the D box.
It gets screwed around it's perimeter anyway.
What I Don't like so much is the condensate kit and its added 1" foam gasket material thus raising the entire unit off the roof that much more than the standard 3/4" gasket.

Ditto with fit of D box. Mine didn't match curve of roof but those screws did their magic.

After one year the 4 bolts that hold the Penguin II down and compress the gaskets were finger loose. I retightened the bolts to what I thought was reasonable torque. I then looked on the roof and the second gasket (the one that came with the condensate "cups", not the grey foam gasket glued to the bottom of the Penguin II) had compressed down to almost nothing.

Hasn't leaked yet, so I guess everything is good. Another year has gone by, so I should check again.