Jesse,
I'm not an expert on the 110 motors but I read somewhere that the big motors will carbon up from lugging the motor. It stated that we can do more harm to the motor by not keeping the RPM's ups. They said to run between 2600 & 3000 RPM's.
So I've changed the way I run my CVO & run 5th gear most of the time. 6th gear usually at interstate speeds of 75+.
We just got back from the same area you were in & found myself shifting into 6th gear below said RPMs & then down shifted to 5th. I will try & find the information on lugging & carbon build up & then pass it on. I know somebody else has seen this write up or can give us more info on the subject.
Sorry to hear about the break down so far from home. After it is all fixed & back home in the garage it will be something that you will be able talk about your trip. Back in 2001, 2000 miles from home I blew a head gasket on my FLT EVO, 100 miles out of Sturgis. I had it trailered into Sturgis & we rebuilt it in the camp ground. We had it running by 9am the next morning. No down time for that Evo! It got me back to Florida & I didn't tear it down until 2004.To this day my friends & I still talk about rebuilding it in Sturgis.
Get it rebuilt & ride it!
I'm still riding that old FLT 23 +years!