T-111 is a massive problem due to the poor manufacturing process that leaves voids and also problems with ply glued properly.
T1 11 is going to soak in moisture eventually I would think having a corrugated rainscreen behind it would dry the back out.
Even painting the back may cause moisture to be trapped in the sheet.
If possible use Hardie lap siding with Plywood And corrugated Vapor Barrier underneath.

--
For full context, visit https://www.homeownershub.com/mainte...dge-11821-.htm