I've always wondered if they could program one "non-movement" car to run in Dinosaur. Sort of their version of the Green Team on Mission Space.
Over at Star Tours, if they have a simulator that's not being used, they can run what they call a "Flight Test", which is the full show minus the cabin movement. You see the movie, the lighting and audio effects, but no cabin movement.
On Dinosaur, they could have one vehicle that's programmed to stay in a fixed position the entire time. So you'd still drive up and down the hills, the dinosaurs would still jump out at you, but you wouldn't be thrown around. (If a static vehicle would still be too jarring, they could even program the motion base to "ease" the vehicle through some of the drops and hill, and "bank" the curves virtually by tilting the motion base at the proper times.
They would just need to make this option known to those who would be interested, and create a way to wait for it, kind of like the wheelchair accessible boats on Small World. (A separate queue of some kind, because it would only come around once every 5 minutes or so). Or perhaps make the vehicle so that it can be switched from one program to the other by the CM at the boarding platform, though this would open things up to a CM forgetting to switch the vehicle, and then someone being sent out into the attraction who would get hurt by the regular motions.
Sure, it would cut into the hourly throughput of the attraction and increase the wait times a little to have this vehicle that might not always have people in it, but it would open the attraction up to people who wouldn't/couldn't ride it normally.
-Rob