Me to the rescue!!
I have used 100 ft of low loss coax ($18 on amazon) without issue EVER. I have the Tailgater and the 211k.
I then hooked the 100 ft to another 50 ft using a cheap Radio Shack connector. 90% of the time it works perfectly. Sometimes, it won't start looking for birds, and then you reboot it and it starts. Very rarely, it won't work the second time. It has ALWAYS worked by the third time.
CAVEAT: I have a bulkhead pass-through entrance (a glorified hole) in the side of my TT, which the coax goes through without any connection and directly to the 211k.
Picture quality has never been an issue. Getting power out to the finding servo "can" be, but usually isn't (as said previously). Make sure any power cable is well away from the coax, or at the minimum crosses it to the perpendicular. A parallel power cable closer than a foot will destroy your connection.
Good luck!