Here is the Balloon Fiesta site for camping options:
The Albuquerque International Balloon Fiesta - RV Information
We were there 10 days last year and parked in the dry camping spots with a specific group. In our area there would have been plenty of room to park your trailer.
At the dry spots there was a shuttle that came around continuously throughout the day starting at 5am to after the night festivities ended. It took you to the liftoff grounds in 10 minutes time so we didn't have to walk to get there.
I would highly advise that you use some kind of festival camping as the congestion for driving in from the outside area was horrible. They also close some roads down at times for the traffic so it's just so convenient to stay on the festival grounds.
We signed up to help crew which was a great experience and we got a free, very long ride for doing so. It was awesome!
If you have specific questions just call the fiesta office.
For those of you planning to go next year, they'll be taking RV reservations starting around Oct 20 or so. Plan early!!
Note that the outside area RV parks up their prices during the Fiesta - parks all the way up to Santa Fe. It's a VERY popular event.