I installed a KVH dish above my kitchen (mid coach) on our 31Y Adventurer. There's about 12" of cable exposed on the roof. I used the A/C duct to run the cables to the front. The duct was only abouut 14" shy of running right into the front cap area. I just pierced a hole in the foam. I used some homemade hanger wire staples to secure the cables in the duct.
I also used through bolts to mount the antenna. Worked out great, and no issues for the past 2 years or so.
I took pictures of the install, and had them at the photo gallery. A crash took them out a while back, I assume they are gone forever from the site. They are still on a CD somewhere, I'll poke around a little, the install worked out very good.