Planning ahead to take time off

I have booked two vacations for next year and have tentative plans for two others. I got a message from my singles cruise group about a private cruise in the southern Caribbean next July. This trip (on the 236-foot S/V Mandalay instead of a cruise ship) starts and ends in Grenada, with stops in the nearby Grenadines. I will definitely work on losing weight since the cabins have bunk beds, and there's at least a 70% chance I'll be in the top bunk.

I've already booked everything for Furry Fiesta 2016 and will likely also attend RMFC 2016. I would like to go to Biggest Little Fur Con in May, but I'm not sure if that will be possible.