Unless something has changed recently, park-to-park buses start running at 10 a.m. So, yes, Uber/Lyft is your best bet.
If I were doing this, I'd take a resort bus from DAK to either the Contemporary or GF and then walk or monorail to MK from there.
BTW, Uber will drop you at the TTC, so you'll still have to get to MK from there.
ETA: I was posting simultaneously with the above posters!