Just bought an enclosed trailer. The interior is bare plywood on the floor, ramp and 2/3 of the way up on the walls. I'd like to seal the interior to protect it. I live in AZ so "grit" can be an issue, not concerned about water. It will be used to haul sound equipment, most of which is on rubber wheels.
I was thinking of using a solid stain for decks? What do you all think? And water based or oil based? I'd like it to last and don't mind any extra work at application. Any other suggestions?

Not sure it's even worth it.
I've had up to 4 enclosed trailers for many years that got use every day for constrution work and they all still look great.
I'm not seeing how a stain is going to do much.
If I was going to do anything I'd use epoxy porch and floor paint.

I actually am now thinking a floor and porch paint would be best.
I want to be able to sweep it clean. We haul electronic equipment in cabinets that are on rubber wheels. I want the trailer to be clean so we are not imbedding dirt into the wheels and then rolling it in to studios and performance halls. Does that make sense Joe?

I think an oil base floor paint would be best, but boy, is it hard to find.

Think this through. You get your trailer floor and ramp if it has one cleaned and painted. What happens the second the wheels come off the ramp? At some time there going to be running over the ground and along floors that you have no control over picking up dirt.
Your intentions are good but in real life not pratical.