We have been driving -very slowly- towards Argentina for the last year and a half, we have been in Colombia for a little over a month now.
We have slept in our RTT over 355 days since we have been on the road, and would not dream of doing the trip without one. It has truly been the most comfortable and convenient "home" for us. You made a wise choice buying one, don't know much about Hannibal RTT, but Hannibal awnings are the best.
For the rack, have you looked at a BajaRack? That is what we are using and it has been great.
If Dave Connors is already in touch with you then you have a solid source of info. If you have any other questions drop me a pm.
Hopefully we sill see you on the road,
Luis