Surely chartering is the way to go?
There are enough Gulfstreams in southern USA or Europe to fly large parties between the 2 continents.
There are also enough smaller bizjets to perform the Mexico/Bermuda trips.
A bit more expensive per flight hour, but saves a lot of hassle of owning an older machine and employing your own staff.
I get the feeling that you flying your own jet is part of the reason you want one?