I agree it could be done... but I'm not sure how much benefit you'd get from flying up and down the Florida coastline for 4 hours every day.
If you want to improve your flying so that the CPL course can be completed in close to minimum times, allow more than 8 days. Definitely do some navigation - but try to find something more challenging than following the coast from Vero Beach to the Keys. Stay inland and away from obvious features like Lake Okeechobee, pick routes that transit airspace where you can. Take a day to concentrate on circuits, nailing your circuit heights and speeds, centre-line and touchdown point. Take a day to practice steep turns and stalls. And if you're planning on doing a single-engine CPL, practice PFLS and glide approaches.
It'll take a day or two more to build the hours, but will save time and money in the long run.