I carry a IQ260, 40mm, 60mm and 28mm, and at times 90mm along with rm3di.
You might want to consider purchasing a Factum, as you only need the frame, the guts of your rm3di will fit inside. About 1.5 lbs lighter may not sound like much but over time it will. Not as bulky as the rm3di either.
I use 2 different packs, one when I am working in and around water, i.e. crossing where I need 100% water proof solutions. The other pack I use the F-stop Satori.
https://shop.fstopgear.com/us/products/mountain/backpacks/satori-exp.htmlThe Satori is not as big as it looks on screen and if you are a taller person, I don't think you will like the fit of the smaller packs as the waist belt hits too high up. Great pack, they also sell a rain cover that gives you 100% coverage and it's seam sealed. Will fit in most airline carryon space and if the pack is too big, then just take the ICU out and carry it on the plane, and check the pack. The removable ICU design of F-Stop is excellent.
Battery, be careful on the solution you mentioned as with the IQ the door has to stay open. I am also a bit wary of this since you can't really tell how much heat or discharge the battery is using. Phase One is coming out with a 3400 millamp cell, not sure when as they were supposed to already be on the market, but I would check with a dealer on availability. If you are not going to be ever close to a place to re-charge, the Phase One solution may be a bit tough as there is no AA solution I know of. The whole battery issue is one thing I would like to see Phase One address, net it's not that hard to make a battery with more millamp's that will fit inside the case. You just need to want to.
Storage, never used the Epson style hard drive, however you might try to take along a smaller computer like the Surface Pro 2, and a SSD drive, 256GB capacity or a couple of them. They will download at USB3 Speeds and you won't need to have the laptop on very long, it's just a matter of weight. However should weight much more than the Epson drive as I recall they were not that light.
Ballhead, for weight, consider the RRS BR-40. It will hold your rig, and it's not heavy at all. I use one on my setup when I know I will be going on hikes longer than a mile or so. Knobs are small, and it takes a bit to get used to, but it's rock solid. If you use it make sure you order the clamp from RRS that will accommodate your Arca foot, if you go quick release, or use the screw clamp.
I would also look at the Gitzp 1542 mountaineer tripod, 3 leg 4 section, not too heavy and still will hold the wight of your rig.
Paul
