One option for visiting Dubuque would be to launch in Savanna, IL at the park district marina and cruise the river up to Dubuque. There are a couple marinas in Dubuque where you can tie up overnight.
The stretch of river between Savanna and Dubuque is scenic and not difficult to navigate. You do have to lock through in Bellevue about 1/2 way but generally not a big deal. With my cruiser and with a clear lock, the trip takes about and hour and 15 or so.
One advantage is that towing to Dubuque on Rt. 20 can be a pain. Lots of hills and a couple small towns including Galena that you have to pass through. From SOBO to Savanna would be a relatively easy and flat tow.
The marina at Savanna while not overly fancy has plenty of truck/trailer parking and you can park overnight with little worry.
1998 268CR 7.4L B2
"La Vida Loca"