I've read RG59 is fine for short runs especially in RV's cheaply wired. But. use RG6. For RV purposes, nailing the 101 will bring in the 99 and 103. No dithering required, repeat, for RV purposes. Obviously, an SL3 won't see any thing on the 119 but I thought no HD was on that bird. I'm DNS so I don't bother with locals, so I really don't know. Sounds like the OP has a clue and is learning fast.
Biggest friends are Dishpointer, a good compass and level, good numbers (there are apps for that), and couple hundred buck meter. When all else fails the too expensive Align-a-site will get it done. I've shot through a ten foot foot window in a giant redwood stand at Trinidad, CA.
Somewhere here, I posted a pretty good guide. Bottom line is pay attention to detail. Always start with a plumb/level to earth mast unless using an Align-a-site (it don't care). Using a good compass with no local anomalies (deviation), you will have signal. Being it isn't a perfect world, sometimes you will struggle.
For the experimenters, my Avatar is a "Dish" small oval (23"?) with an SL3 on a modified boom. Works fine IF you are good at signal getting. I went back to a Slimline as it was so much easier. Still the "Dish" was much smaller and lighter.