Finally to the point of ordering everything for my D-SLR underwater rig. I'd like to start by thanking everyone on this website (plus a few others) for the advice, guidance, and direction.
I think I'm down to the "last" piece - at least for the initial test run to Cozumel in April: A collapsible cooler to transport the camera to the boat and use as a personal rinse-tank on the boat.
The rig will be a Nauticam NA-D90 with 5"standard /8" float UCLS arms with Inon D-2000 strobes x2 and either a 105 flat port or Zen 100 mini-dome.
As the cooler will have to be packed with all other check-on dive gear (am I going to have any room for regular clothing?) I'd like to keep it as small as possible.
So, based on experience:
- 24/ 36/ or 48 can size needed?

(Of note: Ryan at Reef Photo suggested a 48 can size of the Polar Coolers, but those seem to have much more padding internally than the AOCoolers and therefore harder to fold for packing)

I second the Polar Cooler 48 can size. Gives you enough room to pack your rig, plus a couple of towels, a jacket and a topside DSLR. I just used in Isla Mujeres with all that stuff in the bag unzipped.

I also used it as a check in bag with all my clothes in it...tight fit but it worked.

Mike

i went with this soft sided cooler for almost the same rig except i am using the flat port 50

http://www.amazon.com/gp/product/B001MCE4NO/ref=oss_product

it folds pretty flat for packing in checked luggage

Just back from COZ and used the polar cooler 24 pack for my rig and it worked great for to/from boat transfer and on the boat - unzipped. My rig was a Nexus D90, 5"+8" arms, two Z-240 strobes, Nexus 1017 mini-dome. Its a snug fit for my rig but I liked it and it worked well. A big dome would not fit. I originally bought a 48 but it was larger than I needed/wanted. I carry all my gear (housing, ports, dome, lenses, camera body) in a Lowepro backpack for plane transport.
The 24 would not be large enough to carry all that you mention in your post on the plane. I squish my 24 down to minimum size and it squeezes into my dive gear back in checked luggage. If you really kneel on it, it can get down to just slightly larger than a padded regulator bag.
I notice the 24's are listed as backordered until mid-May on the Polar cooler website.
For bringing on the plane with all you listed, the 48 seems the size for you.
Either size makes for a nice rinse tank.

I have a Nauticam D90, 5"/8" ULCS arms, 2x Z240, 105mm ports, 8.5" dome, etc., etc.

I use a 48 pack soft sided cooler and it works great (http://www.aocoolers.com/index.cfm?fuseaction=product.display&product_ID=6&ParentCat=22).

Tried a smaller size and it was just too small. I only use it for local boat diving though, so cant comment on packing it for travel. It is pretty well padded, but doesn't fold down too well. I could see packing all my clothes and some extras and checking it in as a separate bag I guess. For travel diving I pack all my dive gear in a rolling duffel for check in, all my housing/uw gear in a Pelican 1564 for check in, and my camera equipment (body and lenses) goes with me on the plane.

For packing for local boat trips its great. Holds my rig built and works as a great private rinse tank.

I have the American Outdoors, www.aocoolers.com 48 pack and like it a lot, packs easy and seems to be very durable. A couple of nice things about this company are that if you order a 36 and it is too small as I did then you can return it for a full refund less skipping or exchange it for a 48 that fits my Ikelite with strobes and a 8" dome. From there website Our Guarantee Covers: * The Liner: If it ever leaks we will replace it just $12 for shipping.

yup. same experience with the AO Coolers. very sturdy and padded. i also originally thought i could get away with a smaller size, then shipped it back and easy replacement for the larger 48. highly recommended.