Okay, I'll take the first shot at this. I'm a little confused why you would need a BrakeBuddy with a tow dolly. The dolly should have its own braking system, either surge or electric. If it doesn't then you need to upgrade to one that does or add it to your existing dolly.
A BrakeBuddy is used if you are towing with all four wheels on the ground (no dolly). It provides a braking assist by applying the brakes on the car at the same time you apply the brakes in the motorhome. You will need a tow bar, base plates and tail light wiring for the car to tow four down.
I don't think the Maxima is towable 4 down unless you install a transmission pump. You would have to check with Remco for availability for that.
I think you need to let us know what you are trying to accomplish and maybe we can provide better information.
2013 Excel Winslow 34RKM
2015 GMC 3500 Denali Duramax 4X4 dually