We'd lift DD in if she went on, so we would not have a problem (our problem would be whether the restraint would hold her since she's pretty tiny). It does not look like there would be anywhere for you to hold onto to haul yourself in, but I think you are right about not knowing unless you see it.
I can give you some info about Test Track. They have a trial car (I'm not sure where it is, since I have not seen it, but several people have posted about it). Something I know they have for sure is a seat level transfer point (we used it with DD). The ride car is similar to an actual automobile and the usual boarding area has the car below you so that you are at sort of dashboard level and step down into it. Unloading takes place at the same site and involves a big step up. But, there is an alternate boarding area where the car is just sitting on the track in the same position that a real car would be if you pulled up next to it. You can pull you wheelchair right up to it and the car is on your left. We still had to lift DD in because she can't make a sliding transfer, but it was more like transferring to the side of a bathtub (since the car door is solid and doesn't open) and then swinging into the tub. Your wheelchair stays there and you unload at the same place. Anyone who could make it into the old subs would probably find this a piece of cake.
At AK, most of the attractions are either wheelchair accessible or shows. Three that require a transfer are Dinosaur, Kali River Rapids and another dino one (I can't think of the name, but it's not TriceraTop Spin). Dinosaur has jeep-like trams. Wheelchair guests board and unload from the left side of the car (the car is to your right) and you would be able to get your wheelchair pretty close.
Kali River Rapids is a round ride car with seats along the circle, facing into the circle. The regular boarding area has the boats moving slowly along a wooden boarding dock. For wheelchair boarding, they have a clever arrangement that "captures" the boat and holds it secure in a gate until they release it. The door to the car is fairly narrow and the floor of the boat is a step down. The seats are fairly close (but I'll have to look on next trip if they would be close enough to transfer easily). There is a seatbelt that you share with the seat next to you. There is also a rail above the floor to keep your feet on so they don't get wet. We got DD's feet on it, but as she gets excited, she goes into extension and her feet came off the rail and ended up on the floor. He shoes and socks were totally soaked. DD, niece, DH and I got a little wet, but my mom was with us on the ride and she got totally soaked (down to the underwear). At the very least, I'd suggest bringing a change of shoes and socks along. DD's feet were cold as ice and had some pressure spots by the end of the day in her wet shoes.
The other dinosaur ride is sort of a cross between the teacups and a roller coaster. You spin at the same time as going up and down. You board and get off at the same point with the ride car to your left and can pull the wheelchair right up to the car. The restraint is a pull down shoulder restraint. DD had problems with this ride and was almost out of her seat by the time it stopped. I don't think you would have a problem if you don't on the teacups, but DD has mixed CP, spastic quad with dystonia and athetosis, so she has a lot of trouble holding her position when she's excited. She couldn't hold on or scoot herself up when she got thrown around by the spinning and she slid under the shoulder restraint because she's not very big. Needless to say, unless they add seat belts, she won't be going on there again.
My daughter rode on Mission Space on July 4th and her dad reports they have a capsule with a seat that extends out of the capsule for loading of handicapped persons. He just transferred Jackie from her wheelchair on to the seat and then the seat was returned to the capsule - biggest problem he had was climbing over her to get to his seat 
