I don't know R-Vision or the styrofoam as a specific issue. Wondering if it's one of a couple of things. Trailers are typically not cleaned out very well before they leave the factory. You can often find sawdust and debris in all sorts of hidden nooks and crannies and even in obvious places like light fixtures (like our new TT). Am wondering if the same thing could apply to foam debris?
Perhaps you have still had a critter nesting in the AC unit or "leftovers" from a previous one? I'd take the cover off on the roof and see what you can find. Not sure what they use for duct material but am guessing it's the same "coiled" plastic stuff used for RV heating ducts (similar to a dryer vent). Since it doesn't have smooth walls, maybe bits of foam have been there from the beginning or from a critter and have been sort of stuck in there from static elec. or moisture?
In any event, I'd take the ceiling outlet vents off, the interior AC cover off and the roof cover off and try and vaccuum any debris out. A little gentle compressed air (probably not higher than about 30psi) would help to blow it out as well. Could get messy inside so be prepared. Also, you'd want to try and get a vac hose in as far as you can into the ducts.
Hopefully you have not had some rodent or critter chewing at plastic ducting that exposed foam somewhere in the ceiling. Wouldn't know if you have block foam or batt insulation in your ceiling but it might be nice to know. If it's batt type, you'd know it's not from something chewing at it.
If you have had a critter in there, you would need to prevent them from getting in again. You could add some metal mesh to the roof vent. I know from experience that mice can get in through some pretty tiny openings that you would never think possible and hopefully you don't have dead carcass in there. Anyway, just thinkin' about what it could be and what I'd look for..... If you do find out, please post what you find.
Gil & Deb & Dougal the Springer Spaniel
2014 KZ Spree 262RKS & Ford F250 supercab V10 4x4 LB