At Universal Studios in Hollywood, there aren't that many seats that are restrictive.
The Mummy is a coaster, however they do have test seats in the front of the attraction that you can utilize to see if it is a comfortable fit.
I hope this helps.
The Mummy test seat has been pushed back from the entrance of the attraction to just inside the queue though the restraint is very tight fitting and it's likely you won't be able to ride.
The Simpsons, JP and Transformers all have a single lap bar for each row. Transformers shouldn't be a problem since it was designed with all types of people in mind. JP is also relatively new so if you can get one click, you're good. The Simpsons should be ok if you sit in the back row since they're slightly larger than the front row.
Hope you still get to go to Universal! Have fun at WDW!
What I mean is we are going to WDW now but on my way back to Australia I am stopping over at Anaheim on the way back on my own while he goes back to Australia and university. I intend on checking out DLR and Universal CA