I know of no other van gatherings referred to as Rubber Tramp Rendezvous other than Bob's. But I think I've seen one or two van meet ups advertised in other areas referred to as RTRs - not 100% sure.
There is also something called common law trademarks - you can google that one.
Something...
here's a new product about to hit the market that may be of interest to van dwellers
https://www.kickstarter.com/projects/1253665084/zero-breeze-the-worlds-coolest-portable-air-condit/updates