The Invisibrake worked well on our 04 CRV with no issues.
However, be aware that there were very early credible reports of false braking including when not towed. Roadmaster did not acknowledge this and I don't know if they made any changes.
And be sure you understand the battery charging part. As I recall the only possible charging occurs when the lights are on - ie the power comes from the light circuit. So the lights must be on and even then charging may be inadequate. My 04 didn't need charging but newer cars may have much more drain like navigation being on when towed.
For me there is very little additional cost to just using a 6 wire cable which has heavier ground and charge wires. On both my CRV and Jeep I also connected the spare wire from the toad brake lights to a MH cab light so that I know when the toad brakes are applied. I bought the Jeep set up with towing including the Air Force 1 brake.
2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland
Bob