Bruce: I think there is a bit of a difference in carrying a big kit in your canoe and carrying on your back. I think a 2-lb is too much for backpacking especially if one can restock once a week. Something in the 4-6 oz might be all he needs. I don't agree though that one of the two hikers should carry the FAK. It should be split rationally so that both have at least a minimal use kit.

urbansurvivalist: There are a few things I would eliminate right off the top. Items should serve dual purposes when you are carrying everything on your back. Toss that white tape in favour of your duct tape in your survival supplies. Teabags can be obtained from your kitchen kit. Bring only as much moleskin as you need - prior experience should tell you if you actually use it, again duct tape can double for moleskin for some people. Trim the meds, bring only what you really find useful and that you respond to. Instruments? have you much experience with the equipment? CPR barrier - how well do you know your hiking partner, you may not really need it. What are you protecting yourself from? Venom extractor (even a Sawyer kit which is the best of them) can be deep sixed IMHO.
Separate LED light - should be part of your ordinary gear. Water purification tabs - don't your already have a main method of purifying your water.

In short, trim out the stuff you are already doubling up on with the rest of your kit. Reduce the quantities using your best judgment and then split the kit into 2 for you and your partner.

One thing you could do if you decide to carry a full kit - after your first week or two on the trail reevaluate your entire pack. You may find that you really don't need and/or haven't used a good deal of your kit and pare down. Mail the rest to a buddy or to yourself at home or to a General Delivery address further up your route so that you can grab it later.