I have the 507 and the 510 systems. 510 is for marine use so it's on my boat trailer. Before I go repeater route, I recommend you try to place the base unit up high. In my case the best spot on the 507 unit is the sunroof, passenger side (suction cupped) with the display pointed towards me. It's up high and in a clearer line of sight to the trailer tires. I now only lose a signal about every 1k miles and the signal comes back within 20 minutes on it's own. If you hold it up and the signal works, then consider a longer antenna before the expense of a repeater.