Edit: oops, ground hog day schedule, you got to do day 3 twice, fixed.
With only 5 days aboard you are going to have to make some compromises, but Glovers is very doable.
First day, you will almost certainly be later than planned getting underway so
anchor nearby in Placencia or Lark Caye Range. If
anchor in Placencia, and want to interact with cruisers/locals, then Yolis is a good happy hour choice. If at Lark, you should have enough day light left to get in some snorkeling/kayaking.
Second day early AM (earlier the better): make for Tobacco Caye, anchor off and enjoy Tobacco for the afternoon/evening. May favorite area to anchor is in the sand flats just N of Tobacco and behind the reef, swimming pool calm in normal
weather, about 6' feet (or less) of crystal clear
water over snow white sand, excellent holding, breakers crashing on the barrier reef just in front of you. Beautiful.
Day 3 early AM, make the short (about 14nm) run out to Glovers. The usual prefered anchorage just inside the southern entrance suxs. Go up further north onto the sand flats and anchor there (Im assuming a catamaran). Your local
captain should know this. Glovers is not a good place to be in bad
weather, so check weather before departure. If a front is
forecast, don't go.
Day 4: Enjoy Glovers and the sail back to Southwater. Good snorkeling inside the
lagoon an easy dink ride or paddle way. Excellent
diving outside the
lagoon and nearby MariSol has a full
service dive shop. MariSol resort has a bar over the water and is welcoming to cruisers. You can have dinner there too with advance. Its a short sail back, so you can still have some time to enjoy Southwater. Park rangers will likely collect a park fee from you here.
Day 5: Easy downwind day sail back to Placencia. With a local
captain aboard you can take the inside
route (prohibitted by Moorings otherwise). I assume you have a noon finish so start early.
Tilkal is amazing and popular, but a time consuming side trip. Flying into Flores is the quickest option. Personally, I would focus on Belize and save
Guatemala for another trip. There are a number of interesting Mayan sites to visit in Belize.
Guatemala is the most amazing country in
Central America and is well worth a much longer visit (been my home base for a decade and there is still more to see and do! ).
Trip Advisor is a better site for land travel info.