97 F350 CC SRW 8' bed. 3.55 limited slip now. The better half and I are considering a new 5th wheel camper. Found a few between 8-9K pounds. According to the chart in the owners manual I can pull up to 9900 with my current set up. If I switch to 4.10 I step up to 13900. Tires are factory 235/85 16. I'm worried about hills n bridges with anything over 10K. Will the switch hurt my normal driving mileage much? I'm getting 19-21 now. Also, what will I need to reprogram the odometer difference?