This is the RV that we've been building roof-mounted speaker enclosures for, an '08 Road Warrior Class C motor home and toy hauler. Since it combines living quarters with a garage to store quads and dirt bikes, it's a very popular model in Southern California. | 
The screws are tight, and I like to coat the tops with a dab of silicone to prevent any possibility of moisture dripping into the roof of the RV. | 
Snap the trim rings on each speaker. I like to put a dab of silicone on each corner to make sure they don't come off, especially in the windy conditions the roof will see. |
From this angle you can see the down-firing design of the enclosure, which intensifies the sound in a 20-foot radius around the front door of the RV. This will be the perfect party spot after a day spent tearing up the sand dunes. | 
The completed enclosures are clean and unobtrusive on the roof of the RV, but you can definitely hear them when the sound system volume goes into party mode. | 
The wiring was run in 3/4-inch PVC tubing to protect it from UV deterioration over time. The PVC is held to the roof with stainless steel screws through eye zip ties, and each screw hole is thoroughly coated with silicone to prevent moisture intrusion. |
Now we can mount the speakers, using the included stainless steel screws. Don't forget to connect the speaker wires before screwing the speakers in place. | 
Run a bead of silicone around the outside edge of each enclosure to prevent any moisture from seeping under the bottom. | |