Re-flashing the ecm and changing the air cleaner back are pretty easy, but the trailer hitch uninstall would be another issue for me if I were on the road. I had to put my Freewheeler on wheel ramps and loosen the exhaust pipes to remove and replace the frame bolts with longer ones and then reassemble. With my latest "old guy" issue, Essential Tremors, it was fun trying to get the bolts/nuts installed at the rear above the pipes. Took me a day just to do that.
I was reading some threads on the cost to rebuild an engine. Seems like it was $3,500 to $4,500 for a complete rebuild (twin cam). I'm not sure how accurate the costs estimates are, but if an extended warranty is $2,700 and you could still be denied warranty if a dealer doesn't like what you've done, seems like it isn't risking a lot to go forward without the extended warranty.