Get on it and ride. How do you think people toured before there were such things as "touring bikes"? Why does everyone think they have to have a specialized motorcycle for everything? I've owned three "touring bikes" and my Dyna with forward controls is roomier and more comfortable than any of them.
Like one guy said, "as far as your ass can take it." I've done 3600 miles in 6 days on my Sporty. I've done 3800 miles in five days on my Dyna. If I feel like goin' someplace, I'd jump on either one of 'em in a minute. The advantage of the Dyna is that it holds a whole lot more gas, so you can make far better time on long trips.
I rode an air-cooled Honda CB750 on a 4000-mile trip back in '92. If you wanna go, twist that throttle and GO!
Only advantage to touring bike class is comfort. Well, I got a comfortable home, comfortable job...I don't need no more comfort. Just give me some open road.
Years back I had a 93 FXDL. I put a pillow style touring seat on it and was capable of riding it as far, with comfort, as my current touring bike. The rubber mount motor was smooth and with highway pegs I was comfy. I put 75000 mi on that bike and most was touring.
Way back in 1973 I went on a 6500 mile trip on a Kawasaki Z1 with flat drag bars no windshield and no saddle bags. I had a great trip and even had to ride through 5 days of Gods own rain. Its not what you ride that is important it is that you ride that is important.