If you have spent plenty of time backpacking the AT, I thru-hiked in 1997, then you know how to pack a pack to make it feel comfortable. The same works with using a backpack on the bike. I do it all the time. Instead of focusing on using racks or trailers stick with the backpack. Give it a fair try you might be surprised how comfortable it can be. Either way, with or without the backpack you're going to be sweating and have a sweaty back, it can be with the backpack where you could come up along the AT and decide you want to take a nice stroll along the AT for a while. Oh, problem, someone might steal your equipment out of you panniers/trailer. They can't do that if the equipment is with you on your back. People want to complain about the idea of using a backpack on a bike but quite frankly it's the smartest way of going. In backpacking you learn one thing that is quite valuable in anything you do in life. If you're going to carry something with you make sure it serves more than one purpose. Panniers pretty much have only one purpose...so do the racks. Hence why I use a backpack. I will fess on my 2600 mile trip this summer it took until the last 900-1000 miles before it really got settled in. Some of that was simply because I wasn't in shape for loaded touring. I was in shape doing 1500+ miles a month and actually at the time I was doing 2000 miles a month, but I wasn't doing it with any gear. Yeah after 3 days or so on the first two legs of the trip I had sore leg musces and a bit of a sore butt. I was expecting that to occur on the final leg home. It never did. I was very surprised to have be riding the last 900-1000 miles home and not have any kind aches or anything. I had finally gotten use to the gear weight and it wasn't bothering me anymore...not even on the butt. Kinda reminded me of thru-hiking, you can only get in shape for thru-hiking by hiking.