The tow vehicle for our Sport 22FB is a Jeep Wrangler. Jeep Wrangler drivers usually give the Jeep wave to other Wranglers, so we were used to that when travelling. (This is usually raising two fingers from the steering wheel, but can sometimes be a full wave too.)
I just installed my new Ontario Veteran plates that have a distinctive red Poppy symbol and got some waves from SOBs. At first we thought that the SOB drivers were just acknowledging another RVr, but then deduced, after receiving a wave from an older woman standing outside her house in a village that we went through, that it must be the veteran plate.
I am looking forward to AS waves now too.