Peter,
I’m assuming the antenna requires a vertical mount which is why you chose the ladder. The other option would be to mount it to the crank up TV antenna, assuming you have one, which would obviate the need for a long cable run, but would probably impact the booster’s effectiveness when the TV antenna wasn’t extended.
Since the mfgr recommends the booster be ~10’ away from the phone for good performance, you pretty much have to mount it in the front of the coach. I see 2 options in running the cable; across the roof or under the body. If you choose the roof option the cable can be run next to existing roof items such as the tank vents, solar panels, TV antenna or satellite dish etc. Adhere the cable to the roof about every 3-4’ with Dicor or a similar product. Key is to not allow any slack in the cable between adhesion points as this could result in the cable “flapping” in the 65-70 mph wind when driving. At the front of the coach locate where you want the cable to enter, (I’d assume an overhead cabinet in the front cap). Drill a hole and route the cable to the intended booster location. Since the booster power supply needs AC, the cabinet of choice will probably be the AV equipment one. If so, just be sure to use the AC outlet that stays on when the engine is running (not the TV power outlet). Seal the hole in the roof with Dicor and you are done.
Running it under coach is a tougher and dirtier job. Obviously you have to avoid the slides, but you may find routing paths used by other cables if you open the slides for access while doing the job. Once at the front of the coach, I’d run the cable into the front electrical bay (under driver window) and then up into the coach. I use a hanger wire wrapped with tape and fish it through from the electrical bay. Once it’s through, tape the cable to it and pull it through. The problem here (IMHO) is access to AC for the power supply. The obvious outlet is in the center console. However, this seems to require the booster also be located near the center console. Accessing the overhead cabinets requires running the cable/wire through one of the windshield posts.
Just noticed that the mfgr sells an omni antenna building mounting bracket #901133. This looks like the optimal solution IMHO. Mount it to the roof over the desired cabinet location and drill an access hole for the cable. Seal both the cable entry and the mounting screws with Dicor
In any case, have fun…
Steve