I've worked in the past as a Dish Network installer and as long as you are off shore you should be able to get Dish and DirecTV down to about the yucatan
. But, you may not be able to hit the hi def satellites because they are at a lower orbital position so by the time you get that close to the equator the curvature of the atmosphere is going to start making those signals tough to get. But, even then you should still have access to the 110 or 119 sats.
I just noticed you are going on the pacific side...a little less signal available out there, but should be good for at least part of the trip.