As noted above, single tank side mount is an option with an AL 80. Lateral trim may be an issue depending on your system, but adding weight on the other side will fix most problems.
For travel I use a cam band to retain the lower bolt snap and then use a piece of 550 cord to larks head an upper bolt snap to the tank valve. That allows me to come up the ladder with the tank securely attached to the upper D-ring, rather than bouncing on a bungee.
The tendency for divers to come aboard with the top of the tank at risk of breaking a bungee and swinging around is one legitimate concern of boat captains. An upper bolt snap resolves that issue, and it's still compatible with an old school loop bungee.
Some boats don't mind a diver handing up an AL 80, but other boats may regard it as a burden on the crew or something that slows the boarding process. And, unless it's positively buoyant there is a risk of losing it if it's handed up rather than clipped off to a line first. My preference with a single side mount tank is to just come up the ladder with it on.
If the boat is really SM friendly, it would have a gear line amidships that you could clip a tank to (where pitching in swells is less of a problem), allowing you to come aboard with just one tank rather than two if you're doing deeper technical diving in SM, and haul the other tank aboard afterwards. You could theoretically come aboard with no tanks, but there's a fairly solid argument against being in the water with no tank at all while waiting to come aboard.
I prefer to dive non Catalina AL 80s with a 2 pound weight on the cam band to keep the tail from floating as the tank gets below about 1500 psi.
If you need trim weight to keep the tank side from going low you can add 2-3 pounds on the other side, either threaded on the waist belt, in a small weight pouch, or in a pocket in the wing itself on something like an SMS 50.
The SMS 75 is a little larger than needed for warm water travel, particularly if you plan to dive single tank. I prefer the SMS 50 for warm water travel as 25 pounds of lift is plenty, even with a 5mm wet suit, two AL 80s and an AL 80 stage (our Mexico cave diving preference).
I've found that standard valves work fine on both the right and left side with a loop bungee, so I don't worry about tank availability. You'd be well advised to carry a travel band and bolt snaps even if they claim they can have SM ready tanks available. A small cam band and a pair of rigged bolt snaps only weigh about a pound and a half and don't take up much space, but it's cheap insurance well worth having when the promised tanks aren't there.
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I'm picky about fins and I dive Jet Fins the way God intended. My concession to travel is to switch to OMS Slipstreams which are a lot lighter than Jet Fins, but have very similar swimming traits. In the XL sizes they are too large for a carry on suitcase, but we've had no problems getting all the equipment needed for our Mexico trips, including 3 regs, 3 travel bands, canister light and reels, in a Gne 2 Dive Caddy - and it will still fit in an overhead bin.
