Advice wanted for buying a B+ by travelling Aussie.

A rear entry B+ is going to limit your choices tremendously. If you could tolerate a right-side entry, then I'd suggest a Starflyte or one of the shorter Telstars. If you had more money to work with, I'd add a Phoenix Cruiser model 2100. That is a very sweet tiny rig with big motor home features & capacities in a tiny package. They are most often sold with a slide out, but I favor them without one.