For a 40 kg load, I think you should leave one of the gold bricks at home, and probably switch to a smaller kitchen sink.

Regarding a pack that can carry it, I wouldn't spend too much time worrying about the backpack. I think most good quality backpacks will handle at least as much as the person is willing to carry. I've carried 50 lb loads in my 30 year old external frame with no problems, well no problems with the pack at least. But if you're looking for huge carrying capacity, Dana Designs Terraplane has been the standard in the backpacking community for lugging heavy loads.

Also, a bicycle will allow you to carry a lot more, and if you're worried about the bicycle breaking down, barring any major accidents, it will still work as a set of wheels. There really aren't that many things that can go wrong with a bicycle that will render it completely useless, and they're pretty easy to fix.

But like everyone has been saying, rather than spending time trying to figure out how to carry as much as you can, you'll probably be better off in the end if you can learn how to carry as little as possible. Even carrying 40 kg worth of stuff (what is that, like 80-90 lbs?), you're still not gonna be able to carry everything you could possibly need, there's always something that's gonna be missing. Learning how to improvise and make do with what you have is worth more than a backpack full of stuff.

Like Ironraven mentioned, a good rule of thumb is to keep your pack weight between 25%-30% of your body weight, even less if you're not used to it. I think some people in the military might say up to 50%, but I wouldn't count on being able to do that. I'm not saying it can't be done, but it's not something an average person can do without a lot of training, and you'll definitely pay for it at the end of the day