I've experienced strong current and intense surge when diving the back wall of Molokini, but the water was still relatively warm and clear. 15 dives in those (and more benign) conditions is probably not a good basis to undertake diving in the Galapagos.
Unfortunately, large pelagics prefer those sorts of conditions. The only comparable location is probably Cocos, where the water might be a bit warmer and clearer, but the conditions can still be very challenging.
Without the onerous travel to SE Asia, Palau, or the Maldives, you might be able to experience numerous pelagics in less difficult conditions than the Galapagos further north in the Pacific, i.e. Costa Rica (Bat/Catalina Islands) or Baja (Socorros via liveaboard or El Bajo seamount in the Sea of Cortez) - I have close friends who have dove Costa Rica and enjoyed hammerheads and cow ray schools, I dove El Bajo myself when there were no hammerheads but supposedly they're frequent there, and I've only heard second-hand about the Socorros, with mixed reviews. There's also nice shark activity in Turks & Caicos (we had an excellent time aboard the Aggressor) and I believe shark feeds still occur in the Bahamas but I have never done that personally.
[I'm editing this to thank mjh for mentioning Tahiti/French Polynesia: lots of sharks in very easy conditions in Bora Bora and Moorea, and incredible pelagic activity in the Tuamotu Archipelago, i.e. Rangiroa, Fakarava, Toau - so expensive that it makes Maui look like a budget trip, but the flight to Tahiti is only a couple hours longer than flying to Honolulu and the island hopper flights are just as short as in Hawaii]
Otherwise, forget about sharks for a bit, and go on some dives in your local N. Atlantic waters when conditions are less than optimal. Diving locally here in the Channel Islands prepared me perfectly for the Galapagos since we have dives that are just as difficult and conditions can be much worse than even a bad day at Wolf or Darwin.
You can usually rent gear and wetsuits aboard your liveaboard and it sure would make traveling easier (I always lug my own, but do envy those who rent and only have to tote a week's worth of boat clothes). On my first trip, two divers who had brought drysuits changed their minds and ended up renting 7mm suits from the boat. Also, gear gets beaten up, since you're doffing it in rough water to be yanked aboard by a crewmember and tossed in a pile to bounce around until it's safely back on the mothership. On my last trip, one diver's corrugated BC inflator hose somehow sheared off as it was being dragged into the dinghy and he was stuck with a rental for the remainder of the trip (really pissed him off since he was diving weight integrated and had to switch to a weightbelt, but what can you do?). So letting them abuse their own rental gear might be preferable to seeing your own pride and joy tossed around and possibly injured.