Didn't realize you have the GT. Having your feet "under you" instead of ahead will help big time! I had two cruiser bikes in a row because i wanted to like them, but the seating position was just murder on my @ss and lower back. In the end, before selling the Kawasaki Vulcan i couldn't go 30 km's before lower back was killing me..
If i were you, i'd start with getting R foot controls mounted. Although they don't come cheap, i feel it is the least expensive option, and the one that will be most beneficial!