the long haul trucker is not 'overkill' for lightly loaded touring. hardly. Unless you are credit card touring or being sagged, it's the weight of the gear not the bike that makes any real difference.

I'd urge you not to overthink this, get racks to distribute the weight of your gear on a LHT or a novarra randonne or trek 520 or a raleigh sojurn or any of the other 'value' out of the box loaded touring bikes

and go!

you can put the hammer down while covering a lot of miles daily in style and comfort on a lightly loaded long haul trucker.