Bags, backpacks and toploaders

Imagine that you're preparing for a hike to the mountains and have to take tent, sleeping bag, foam pad or mat, clothes, food, water, drugs, etc. It means all of this stuff will finally be on your back. Now let's assume you are an amateur photographer and photography is the main reason to hike. You have to take a tripod+head, camera body, two or three lenses (10-22/3.5-4.5, 17-55/2.8 and 70-200/4L), filters, spare batteries, memory cards etc.
Of course you can't put it in the main backpack, because it's not designed for fragile equipment and it's not very handy to take off your backpack every time you want to take picture. You also can't take your regular photo backpack, because you have only one back!
What's the solution to the problem? I still don't know. Maybe you have any hints?
As for now I have two ideas. I had three, but one of them didn't work on my recent trip to Havasu Falls (see picture on the left). Aforesaid idea was simple - put your photo backpack into main backpack. Unfortunately it wastes a lot of your space and is even less comfortable to use your camera - it takes at least 5 minutes to take it out and next 5 minutes to pack it back. Waste of time and space. It didn't work.
So I have two ideas left. First is to buy one of LowePro TopLoader bags with special harness and put it on your chest. I have to go to the shop and check how it works. Of course it allows you to put only camera body and main lens on the chest and the rest of stuff must land on your back in special pouches. Advantage of such solution is easiness of using your camera - you can use it without taking your backpack off - until tripod usage is not considered. It might be my final solution for upcoming Phototrip.
The last idea is to buy LowePro Orion AW backpack - it's very smart piece of equipment that allows you to use it as a regular backpack or a beltpack. On the way to Havasu Falls I'd have used it as a beltback - unfortunately it can appear that I'll have a conflict with the belt from main backpack.
I don't have final answer to this trivially looking question, but this week I plan to visit torbylowepro.pl shop and see all the stuff with my own eyes.