On our 2013 Eagle 284 BHS TT, there was no wiring around the bedroom roof vent aside from the optional 120v wiring for a 2nd AC unit.
The closest 12v wiring was the power lead for all four of the lights in the bedroom area. Four lights seemed to me like a pretty significant load on a single fuse already, so I didn't want to put additional electric load to it. I decided the only option I had was to add another 12v line somehow.
I started at the electric load center by figuring out which wire was for the next unused fuse position. I pulled the oven/stove forward and removed the microwave so I could access the spaces behind/under those. My next problem was getting the new wiring from the load center on the floor up to the ceiling.
The stove/oven and refrigerator were next to each other. Just below counter level just aft of the oven, I CAREFULLY drilled a hole through the wall to get my wire into the refrigerator space. (I want to stress, I did not drill into the refrigerator. I just got inside the cabinet where the fridge is installed.) Once in there, I ran it up the wall to the level of the microwave where I made another hole and brought the wire into the cabinet space for the microwave. In that space there was a bundle of existing wiring going up into the ceiling. About 18" from there, was a ceiling mounted stereo speaker. Once I had my new wiring into the ceiling, getting to the speaker hole in the ceiling was rather easy. The next puzzle was getting the new wiring from the speaker hole forward to the air conditioner location. Feeling around inside the speaker hole I found several wires. One of which was the wiring for the thermostat going to the air conditioner. I undid the t-stat wiring at the AC unit and attached a 'fish' wire to the end. Then I pulled it back to the speaker hole where I attached my new wiring. Next I just had to pull the wiring back forward to the AC and reconnect the t-stat wiring to the AC. Once there, I figured I could use the AC ducting going forward to the bedroom like conduit. I just had to fish the wiring forward through the ducting to the bedroom. I removed the AC outlet vent in the bedroom and brought my wiring to that point. From there, I literally only had 6" to go to get into the square space for the roof vent. One more hole and I was there. A bit of silicone sealant sealed that last hole exiting the ducting into the vent space.
Then I installed the Fantastic fan per the instructions. I re-installed the stove/oven and microwave. Since all the holes I made were inside the spaces for the stove/oven and microwave, absolutely nothing was visible once they were re-installed.
So now we have a Fantastic fan in our bedroom with a dedicated fuse supplying power to it.
FAA A&P mechanic, ex-RV dealer parts dept
Retired B-52 Gunner/Flight Examiner, B-52 Crew Chief
2016 Jayco Eagle HT 29.5 FBDS w/ 15,000 BTU AC, 50 amp service, upgraded counter top, thermal pane windows, elec. stab jacks, outside grill, backup camera and MORryde pin box.
2011 GMC 2500HD DURAMAX/ ALLISON