As a single rider, you'll be able to go in the single rider line, so that will expedite things for you. It will also help if you eat on the go all day - QS instead of table service.
It can probably bo done if the parks aren't very crowded. I didn't catch what time of year you plan on doing this. If it's like Christmas season or spring break, then it will be tough. Otherwise, DH did this last June (business trip to Orlando). He was able to do everything he wanted, and even did a few things twice I think. At MK though, he was going by HM and the teacups of all things, saw no line and went on...but then he missed out on Splash and BTMRR. He just missed them. I am certain he hit Mission: Space, TT, ToT, RnRC, EE (twice), Space Mountain (also more than once, I think), HM, and the Teacups

!
It sounds like you have a day by yourself to drive up to WDW alone fromsomewhere else in Florida, but if you are planning on going for a week or something and just trying to have a day to yourself, I agree that using a baby swap would also be a good strategy. We often split up briefly at WDW while doingthe baby swap. the area near SM in MK is one of the best areas since there's several things for the little ones to d while the adult are on SM (peoplemover, Buzz, Rockets, gift shops, arcade)