Anyone ever used TrueCar or other car buying type companies?

I am looking for a new (or newer used) vehicle for my wife. 4Runner or maybe Highlander.

I have looked at Vroom!, Carvana, Car Gurus, and AutoTrader. They all are about the same or within a few hundred $$ of each other.

I went to Samsclub.com to see if they have a car buying service, they do, they use TrueCar. While I was poking around TrueCar, I found out they offer a special discounted rate for Veterans, supposedly up to as much as $4,000 below MSRP. Only concern I have is that there are apparently no TrueCar participating car dealers in Kentucky, the closest to me are all in Indiana. I really hate the idea of purchasing out of state, as there can be some problems with getting the vehicle registered in my state. Just went through that when we bought our travel trailer in Nevada in April, then tried to get it registered in California.

So, just looking for any thoughts on possible ways to get a decent deal without having to argue with dealership sales people.

Much appreciated