18+ pounds base weight is NOT unpleasant! It is the total weight on your back that makes for "unpleasant". For a weekend trip, 20 pounds base weight + 3 pounds food and fuel is still a very managable pack.

Each person's comfort break point is different. My personal break over total pack weight is 35 pounds - at this point the pack actually makes me choose to do less miles. I can do 40-45 pounds, but have to change to a different pack that has a sturdier suspension system rated for that weight and cannot do 12-hour days. 30 pounds is more comfortable, for sure. Over the years, I have settled on a base weight of 20 pounds (including bear cannister which is required where I backpack).

A more standard measure is percentage of "lean" body weight. In other words, your ideal body weight. About 1/4 your body weight is commonly thought of as a good pack weight.

There is trail comfort and camp comfort. You have to find a good balance between the two. I can get by with a small sleeping pad (8 oz x-small thermarest) but am the coldest sleeper in the world so my sleeping bag is a 5-degree bag, which for me, is good only to the 20's. If I took a lighter bag, my pack would weigh less but I would not sleep well. Others really need a hefty sleeping pad (many over a pound) but get by with a much lighter bag.

And then there is why are you out there? Fishermen will throw on many pounds of fishing gear. Climbers will throw on heavy climbing gear that often out-weighs their base weight.

The longer the trip the more food and fuel you carry, so the more careful you have to be to really minimize base weight. Food weight should run between 1-2 pounds per day. Really hard to get enough even with FD food for under 1 pound per day. Over 2 pounds per day and you probably are carrying the wrong kind of food.