Been through something similar with a Stellarvue mount and SV80ED refractor (f/7). Bought a used Manfrotto 058 and it worked well enough but the thing was heavy and still pretty long when collapsed. It wasn't something I could just throw in the car (Corolla size) if the whole family was going on a trip.
Years ago I had a Tele Vue Panoramic mount and it was much lighter yet was stable enough for a 80-90mm scope, so if I was you I'd be looking for something similar to the Panoramic tripod.
The Berlebach Report tripod that Vixen sells with a version of its Porta mount is similar but I'm not sure about the fitting.
http://www.bhphotovideo.com/c/produc...uy_alt_az.html