I do the same the majority of the time. I have done quite a few finish outs with Stain, paint like Flex-Stone and carpet,and even Vinyl. To me, a finish on the enclosure is all about the individual of wants of eye pleasing.But I do the same as you majority of the time.To be honest I don’t use anything. Haven’t carpeted a box in 20 years, I just leave them bare wood as I like testing stuff, swapping stuff around, subs, boxes, amps, etc, so hasn’t made any sense to carpet or apply any finish; nothing I put in my car is permanent so no reason to finish it, unless I put in a temporary prefab box already carpeted. But, when I have finished a box, it was in box carpet or spray paint or exterior house style paint.