Readybrake prices

I have no issue with putting magnetic lights on the top of my yaris. It's a 2007 and has nearly 175,000 miles on it. It won't mess up anything. I am having a hard time though deciding on whether or not to go the rout of the 4 down or the tow dolly. I know I won't have this car forever. It could last another few years or it could be gone tomorrow. I hate to spend the money on base plate, wiring, brake wiring, and the labor on it and then have it for only a little while and then have to spend that money all over again for another vehicle. My wife has a new explorer and we would set it up for 4 down, but it's too heavy. The curb weight of it is over 6000lbs and our motorhome is rated to tow 5000lbs. Curb weight of my Yaris is less than 2300lbs.