i think that is a really close squeeze for time. if you leave Universal at 7 (assuming you have your own car), it could take 10 minutes or so with traffic to get back to WDW area. Maybe longer. I would just be worried about making it all. HDD does make you check in at the window usually first too. If you left Universal earlier than 7, then it might be doable and keep in mind the long walk to the parking lot from Universal back to the car too- build in time for that. If you are driving to FTW, you have to park at the main check in area and board a bus to the Pioneer hall area where HDDR is. You can be sitting there waiting for a bus for 15 minutes (last time we waited almost 20). You can't park directly at Pioneer hall. just something to keep in mind.....i think it is a tight squeeze and as someone else said, i would be stressing the whole time.
Are there cabs that go from US back to FW or do we have to rely on resort transportation? If we leave at say 6:30 - do you think we could get to FW by cab for a 7:30 or 8PM sleigh ride? then Hoop Dee Doo is at 9:30... I just don't want to make 2 trips to FW and am trying to squeeze in the sleigh ride while we are going there for Hoop Dee Doo!