I think that makes good sense... it's a very strong part of the hull, and with the proper backing as you describe should be fine.. You want to be sure to caulk it properly so that future leakage is not an issue.
And you need to be able to accept the look of it - it's a bit unconventional but I can't see it doing any harm.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)