Man, at 5'3", The DT will fit you like a glove. You can probably use the upper footrests too!
As for knees sticking out, it depends how you sit. My knees genrally stay paralell. Some people like the 'spread eagle' for their comfort - and knees in the wind. LOL!
The DT is good for a few seating positions for me:
Feet behind, lean forward (land speed record attempts)
Feet under, back straight (standard)
Feet under, lean back (cruising)
Feet up, lean back (snoozing)
The wind protection is pretty formidable on the DT. The only way you'll really know is to sling a leg over one - Then you'll know if it is going to be right for you.