extremely hard to moonlight with just an internship.
Reason- There's plenty of people to do it that are better trained than you.
ER/FM/IM residents in their 3rd year or board certified physicians working part-time or in-between jobs.
Best bet is an urgent care center, but your competition will be the docs I listed above. Be sure to do an ER month during internship if you want to be remotely competitive for that.
Other option is research in whatever you might want to pursue as a fellowship. Pain, sports, etc.
You can find funded research spots at most major university medical schools as an MD. This will be hardest away from a hardcore academic center. Sorry but tampa doesn't count for that.