Welcome to the board.
I am going to take a little bit of a different approach. IF you are going to continue to travel then a lighter BC for travel is in order but not necessarily a "travel" BC- one that is sold as such. The Ranger weights in at 9+ pounds and takes up a huge amount of space in your suitcase. In addition, there is simply no need for that much lift or rugged design, plus for warmer, easy summer diving you may find your "travel" BC nicer to use (I did). I don't really like the BCs that are billed as "travel" BCs. They tend to be pricey and they reduce weight too much at the expense of quality- the Zuma for example has thin 1/2 wide shoulder straps- too light IMO. Since you are familure with the Zeagles, consider either the Scout or the Express Tech. Both are built like Zeagles but lighter, each weighing in at around 4 lbs, pack in 1/2 the space of the Ranger and are still plenty durable to use as a primary BC. They are relatively inexpensive at around $250. You will likely pay $25 to $50 each way in extra luggage/weight fees to haul the Ranger, so why what not invest that in a BC instead of airline fees (every time you fly I might add). I ended up selling my Ranger and kept using the Scout for all my diving. I now have an ET which packs even smaller than my Scout. The "dive what you are use to" is a non issue. Going from a wet suit to a dry suit is one thing but if you can dive a Ranger, you can dive any other back inflate. Sure it will feel a little different but if that is such a big deal you can't adjust to it in a dive or 2, you have other issues that need working on, no better place than on a live aboard where you will be diving day after day.
For a wetsuit, the water is going to be in the 80ish range, a 3mm is usually plenty for most everyone. I use just a skin or 1/8 shortie in water that warm. A good addition is either a light hood, beanie or hooded vest (best option). These give you a little extra warmth that you can layer if you need it but don't take up much room in your suit case. Regardless, consider taking a full body skin for sun and rash protection. You will cook VERY quickly at those latitudes and nothing ruins a dive trip like a major sun burn.
My best packing advise it to take all of your cloths, separate them into 2 piles then leave one pile at home. You don't need nearly as many cloths as you think and they take up suitcase room. When packing, put all expensive or not easily replaceable items in your carry on. For me that includes mask, regs, computers, camera and meds all of which are packed in a set of clothing (including a bathing suit). A very good addition to your travel items is a 50-75 lb digital fishing scale. 1 lb over the weight limit and the airlines will hit you with a fee. It's better to weight the bags at home and remove that extra pair of shoes than to pay those huge overweight fees.
..... hopefully you'll get a nice easy dive to start off with in Utilla. Liveaboards tend to prepare for people needing to adjust, so the first dive/dives are often "test/try out dives" to see what's up.... for the staff and the customers.
