Using 100-ft of low loss coax with the Tailgater will be fine, I do that all the time. In fact I often use 150 ft (100+50 with barrel connector), and it works most of the time.
FWIW, the barrel connector seems to be a bigger deal than an extra 50 ft of coax. If at all possible, route your coax directly into the RV and avoid the barrel connector. Also, avoid paralleling next to a power cord.
I love my Tailgater so much, I took it to Vegas and tried to marry it. Yes, it is a tiny antenna, but it is very portable, so it is easy to transport and easy to march out to a clear shot of the sky. And setup is very very easy, and that trumps everything else.