There are only two tours offering puffins. Both are very hard to get into, and even if you do, there is a 50/50 chance you will actually go ashore to the islands where the puffins are. At this late date, it is not likely you can get in. Photographers often book two tours, just in case conditions don't allow shooting.

There are several "tours" that are just boat rides and you may see puffins from a distance in the water, but they don't go ashore to the islands where they breed and roost where you can shoot from a blind. Both tour operators go to Machias Seal Island, One - Sea Watch Tours - is out of New Brunswick from Grand Manan Island, The other - Bold Coast Charter Company - ships out Cutler ME, which is a 2 hour drive from Mt. Desert Island.

https://www.nyip.edu/photo-articles/nature-and-landscape/photographing-puffins-in-the-wild


It may be a moot point - BCCC starts accepting reservations in January and according to their website they are fully booked for 2017. There is a waiting list.

It is ideal time for birding - nesting bird counts are:

5000 Atlantic puffins
4000 Razorbills
800 Common murres
300 Arctic terns
200 Common Eiders

There are other birds but I'll have to ask my friend who just came back last week from the BCCC tour what she saw.

You may also see whales, porpoises, seals, and other critters along the way.

This may help if you are ok shooting birds from a boat, or if you don't want to risk transferring from a large boat to a smaller landing craft then going ashore onto wetm slippery, seaweed-covered rocks and wooden boardwalks to get to spend an hour in a crowded blind.

http://www.mainebirdingtrail.com/Puffins.html

Good luck and enjoy the Lighthouse and Maine's rocky coastline. Always opportunities for some outstanding shots there.

This has nothing to do with photography. Years ago there was a ranger walk and lecture "From the Forest to the Sea." The title might not be exactly that, nor might the tour even exist now, but if it does, it will cover the life of the flora and fauna that exist in the area covered and exposed by the tide, which ranges about 12 feet, I think. You can also walk and photograph on the ubiquitous bar of Bar Harbor, which is exposed for almost four hours at low tide.
Don't forget the great seafood, either. Enjoy!

If the Pocket Wizards are the Plus series, they will not trigger the 600 unless you buy a hot shoe adapter as the 600 has no PC connection. It is a good flash and works great within the Nikon CLS, but it is a consumer flash so needs one of these:

https://www.bhphotovideo.com/c/product/767442-REG/Vello_HSA_PSU_Universal_Hot_Shoe_Adapter.html

Just for the record, high ISO is NOT a substitute for flash (or any type of auxiliary lighting). HighISO is great for wildlife, street photography, some natural light stuff, but for portrait work, flash allows for the proper placement of shadows and it is the shadows that are critical for giving bodies and faces dimension.

I picked up a d500 at the end of last year and I cannot believe what a phenomenal camera it is. Nikon hit a home run with this one.

The link from Aloha Bob is a good one. You can do without the big Octa overhead, but two strips on either side are pretty standard for this type of work. You want the two side lights to be the main light with minimal light from the front as it is those two lights that will define the body. A little fill from the front if it goes too dark is OK - but ONLY to kill any really dark areas.

You have a GREAT camera, but no pop-up flash to trigger the speedlights. so you may have to use the 900 to trigger the 600 and just shoot from one side and fill the other side with a reflector.

Sadly, I think you are under-equipped for this type of work, but experiment with the single flash and reflectors to try to get light skimming ACROSS her, not AT her.

I use a mix of water and glycerin for sweat. Here in Colorado, it is so dry that plain water does not stick around long. Mix about 1:4 glycerin:water in a spray bottle. Shake and spray.

It is too late now, but I would have rented any gear that I needed but did not own. I wish I could be more help.

You'll have to experiment with your light so position the light not to soften your subject, but instead you want to emphasize shadows. I'd use 2 lights. One from above subject, and to the side like a Rembrandt lighting setup. Use the second light as the key light on the other side but from the rear. Not behind the subject, but on the side, then move toward the rear slightly. You want to emphasize their muscles so don't use umbrellas. If you have grids to put in the soft boxes then use them. It keeps the light from spreading as much. Don't position the lights too close to the subject like you normally would when doing glamour portraits. Move them back to about 8 feet. You will need higher power with lights further back like this.

Take some shots using side lighting as well. This will put a split shadow on the subject which is going to emphasize shadows again.