I know that I was wishing I had an ultimate Fastpass for that ride, when we were there!
The safari at AK is probably the worst one for this, as you go almost all the way through the regular line, then go off to wait at the wheelchair boarding area. For safety reasons, there is a limit on the number of disabled people allowed into the animal enclosures at one time (you don't want something to go wrong, and find you have 100 guests with mobility issues, in the middle of the lion enclosure
), so the wait at the disabled boarding area can easily be an extra half hour on top of the regular wait. If you are OK to transfer into the ride car, it may be a bit quicker, as you don't have to wait for the 1 wheelchair tie-down point to be available. Just thought I'd warn you of this, so you don't plan anything to soon after the safari - we wouldn't want you missing an ADR!
P.S. Don't try to save time by walking through the line, as it's a looooong walk, even when there is nobody else waiting, and it's not worth the pain to save that extra 15 minutes or so. I know this from bitter experience!