Pretty difficult to set a hard and fast rule on how much stuff is too much stuff. How much you bring depends on where you're going, when you're going and what you are planning to do. If you're using a credit card to sleep and eat in warm weather, you don't need the camping and cooking gear. That ought to drop up 10 to 12 lbs depending on how much comfort you like in camp and what you use to cook with. If you're road touring in populated locations, as least in the US and Europe, you don't need a water filtration system and probably just a couple of water bottles with maybe a bladder for backup if you're worried you might run out. If you're going in the summer in SC you need some bug spray, but not much other than a couple of lightweight shirts and shorts to keep you warm except your rain gear. As mentioned above, you can always buy stuff on the road if you need it and ship other stuff hope if you find you don't need it.

My last tour was an off-road section of the great divide. Since I was camping, cooking, etc in a fairly remote area I, along with the folks I was riding with, carried alot of stuff. My recollection was I had about 40 lb in a handlebar bag and a farfarer trailer, exclusive of the bike, food and water. After a day or two it was the normal load although I did walk up a couple of hills. For cross-training purposes only, of course.

I do think that people tend to overly obsess about the weight and amount of their gear before they go and tend not to worry much about it within a couple of days after they started. If you go up a some hills equal to what you expect to find on your while going out on practice rides you will find out pretty quick if whatever you carrying is too much for you.

Have fun on your tour.