I installed a dome on my previous TT using the supplied screws and sealed with Dicor. I ran the cable down a vent that ran through a side storage compartment. I drilled a hole in the vent pipe, fished out the cable and sealed the hole with caulking. I used small vinyl cable clamps to secure the cable run to the roof and sealed that with dicor as well.
The dome was my high spot on the roof and I always worried about clearance under low hanging branches.
A few times I had to pass on nice camp spots due to trees blocking the dish.
Fast forward: That TT was stolen so I had to start over. Now I have a carryout that takes about 5 minutes to setup. I have a 25' cable and a 50' cable for a total of 75' to work with if needed. I can camp where I want and find a hole through the trees. In the two years that I have used it I have yet needed to set it up in the rain.
I learned my lesson.