I have just about every comfort modification available for the ST (larger windshield, folding highway pegs, drivers backrest, seat modification, electronic cruise control, added wind protection). The riding position isn't BAD. Just not the same as a cruiser. I did a 2300 mile trip last summer and survived. 500 mile days were not unbearable. But my old cruiser with a Mustang seat got me 700-800 mile days without great fatigue.
BTW, thanks everyone for the great information.