First, unless you have already just done it, change the fork oil. Depending on how the ride feels, go with the HD Type E or Type B oil (heavier for a firmer ride, lighter for a mushier ride). Once you have refilled, you can also play with the air gap in the tubes to stiffen or soften the ride (less air gap - more fluid = stiffer ride, and vice versa). Adjust this in increments of 1/4" (both sides) with side to side being within 1/8".
For the back, do you have adjustable shocks on there now? If so, adjust them firmer or softer to get the ride you want. If not, then you may want to consider some replacement adjustable shocks.
Finally, the other thing you can do is to get a replacement seat with more padding and a back rest to offer more support. But reality is that the Sporties are not touring bikes. So they will just not be as comfortable for an extended ride as the bigger bikes.
TQ