The proof house being a one time thing would not give me the warm and fussies to go out and continue shooting with that wall thickness. I think that you have to do the math and see what makes the most sence. Or you might want to think of something like something like drop in tubes or something like that if you don't like the looks or costs of the lining.

Sorry I don't know what an august member is but after all that typing, I just can't delete it.