Dual purpose packing

I've written previously on packing light and the problems that poses. I'm currently in the middle of a similar problem.

On Wednesday I leave for my annual trip to the Lake District, to get in some walking in the hills and to engage in some photography: all the cliched, grand scenic stuff. It's a beautiful part of the world, I love to photograph it.

the problem is, this is another dual-purpose trip: walking and photography. 2 sets of kit to get in the bag, 2 aims in mind neither one really taking precedence over the other. If the weather is wet, I'll get out anyway, if it's fine I'll spend a lot more time behind the lens. It's all good (apart from the part where half the gear I take doesn't get used due to prevailing conditions).

This leads to the problem. The first part is having a bag big enough to get all the gear in. As most of the kit is "hardware" (in this meaning that being kit that has a fixed size, regardless of duration). I might just as well be going for a month as for 4 days for all the kit I'm taking. That's OK, though - I've got used to carrying a bicycle with me so big bags & short trips aren't that much of a problem.

The real issue I have is with carrying equipment in the field. There are great trekking bags & other kit - I've spent a lifetime acquiring it. My rucksack is very nice for a good day out in the hills. I have others that I can use for anything from a couple of days to a whole month self-supporting.
But not with the camera in tow. I have to make all kinds of carrying compromises to mix the two types of gear. Straps for axes & poles aren't terribly well suited to a tripod. I have to have a bag-in-bag to protect the cameras (yes, I'll have both the LF and the DSLR with me every day it's not lashing down). If I were to go with a dedicated camera rucksack it would be weighed down with all the padding, have a bazillion pockets, limited waterproofing and barely anywhere to store lunch, let along waterproofs, maps etc.
Why can't I get a decent dual-purpose something. Maybe a climbing sack with a camera attachment, or a dual compartment set-up that's like a walking sack on top and a camera sack on the bottom. With a proper harness designed for rugged terrain. Not those man-around-town types that come with the camera bags, they wouldn't last half a day with me in the hills.
You'd have thought Lowe, with both the Alpine and Pro camera sides to the brand could get it together. I can't be the only walker who takes photos, or the only photographer who walks out into the hill country.

For now I'll go with what I've got - I'm not splashing out on some half-hearted, half-way deal. Unless my ideal sack comes along, the camera will be down the bottom in a stuff sack, and I'll live with the inconvenience.