I have RA too, developed 2 years ago and I totally empathize with the added strain. Mine is in my hands, feet and knees. I found at the six month mark from surgery I was battling fatigue from the surgery and RA. I started cardio rehab in March of this year completed in Sept. The rehab team was very respectful that I couldn't do certain things ie walking on the track would flare up my Ra, shifted to the elliptical stationary runner and it was great. When the weather here improved in April, bicycle riding every second day for 10 km or so, no hills was far more comfortable. By August doing 60 km a day wasn't a problem but I would have to take a day off if I did that much. The slowest recovery has been my upper body, hands are not good at weight I balance a lot of things in my forearms to carry stuff, it was August until I could open a door without leaning into it. There is a few things I can't do just yet, but they are improving.
RA sucks. The drug - planquil started in May this year is helping. The circulation improvement since the surgery has defiantly made my extremity's work better with the exercise. I'm sure your rheumatologist has told you exercise, diet and healthy living is the best thing, yup, I can sure agree with that. I think in summary for me RA was an added burden but not insurmountable to recovery from surgery.
Wish you the best at finding a rehab program, I'm surprised, all the doctors I dealt with encouraged every time I saw them, but it was a bit of a wait until space in the program opened up. The big thing is knowing your limits and the rehab teams monitoring to slowly get you back into shape.
Take Care, I'd shake your hand if it were possible even though that IS the most difficult thing for me to do. Lots of people do not understand.
Bob