We now have 2 repeaters (one near the rear axle and one near the front) on our 33' MH and don't seem to be losing communication as much any more. We have the TST internal system. The monitor is 19' from the rear axle.
My biggest disappointment was that I paid decent money for the system. And then paid to have the internal sensors installed. And then I had to figure out on my own that I would not get a loss of signal warning for an hour. Then buy a repeater. Then get another repeater. I now have a functional system, but it was WAY more trouble than it should have been.
I do love the internal temperature reading. I believe it is worth the extra work to have the internal sensors.