Clean looking job, and yes to adding a POR15 like product.
We refreshed our 3 X's 8D compartment when we chased the two house 8D's to X's 4 L16's.
Our metal was looking in pretty good shape, with very light corrosion in some areas. We neutralized any acid, then cleaned down to bare metal in the effected areas. Washed all surfaces one more time with a paint prep cleaner. Then three products (Primer, paint (2 applications), top coat (2 applications)), that we got from West Marine. (The gent helping me is a boater, and had learned years before to even treat newer boats with some extra coatings in this high duty area
! So I followed his advice, adding adult beverages and a elbow grease to the effort
!).
This is now about 5 years ago, and with the chassis 8D CAT Maintenance Free battery, and the X's 4 L16 Lifeline AGM's - we have had zero problem with battery gassing/acid attack since then. I do blew the area out with compressed air to get rid of dust build up tossed up from the roadways. And as mentioned, the rear tires will throw some moisture up into the cabinet bottom from time to time. So do yearly brush and soap cleaning of the areas I can reach from above, and all along the bottom. Then rinse carefully and fully with water afterwards. Zero signs of degradation.
In I hope another 3-5 or plus years form now, when the Lifeline's need replacement. I'll go to Lithium, and an AGM starter battery. At that time, I'll close of completely the egg grate bottom, add insulation all around. Add a few up high breathing ports, with probably a pancake fan or two. The insulation, along with I think a small heating pad, will be to help keep the Lithium storage bay within good heat temperature ranges.
I like CC's, do believe they are some of the finest designed and build coaches of any era. But, like with most products, I look at some of the things CC engineers came up with - and shake my head
!
-Air Cleaner intake right on the bottom of the chassis, behind where the rear passenger drives/tags toss up dirt while traveling off road.
-Needed to unattached some of the mudguard's gear to access this Air Cleaner. (Have removed our mudguard, so no longer an issue.)
-The mentioned open battery compartment bottom, behind the same wheels that toss up dust, and water when raining.
-And a few more... but those were the ones that early on with the coach, I wondered 'What were they thinking
!'
Don't get me wrong, respect the chassis, coach, build, etc. - so not really complaining too much
!
Best to all. And OP, thanks again for sharing your Battery Compartment Makeover!!
Smitty