Your plan will work
I totally recommend going deluxe and getting universal express pass plus this gives you an early hour in one of the HP lands each day
If I were you though I would spend morning and evenings both days in HP world - that will give you double the fix but also allow you to ride other rides on the way in and on the way out that are on your must do list
Both HP world’s are at the back of the parks at some stage you have to leave them to get back to your hotels but also if you go back to HP world’s in the evening You have to walk back to them
All these times back and forth you will pass your other must do rides and with an express pass there will be virtually no queueing and you may as well do the rides as you walk past them
With universal express pass and 2 full days you will be able to do every Harry Potter rider 2 or 3 times and every other must do ride 2 or 3 times and feel relaxed whilst you do it
In HP land one morning first thing go to one of the olivanders and get in without a queue and maybe almost to yourself for the show
You might get the wand to pick you if you do!
Don’t miss the ice cream in HP world either!