I'd tape and knock-down or orange peel texture it just like a home ceiling. Most RV ceilings can be done with two to three cans of texture material
Knock Down Ceiling TextureTape up all seams with drywall tape. Fill in holes with spray foam, sand flat and cover with drywall tape. Spray on the ceiling texture. Let sit for 15 minutes. Run a rubber squeegee over it. Let dry, then paint to the color of your choice.
2016 Ford F350 Turbo Diesel SRW 4x4
2017 Grand Design Reflection 297RSTS
2013 Ford F350 Turbo Diesel SRW 4x4 (Destroyed by fire - 8/29/16)
2014 Grand Design Reflection 337RLS (Destroyed by fire - 8/29/16)