So understanding your sit-rep and re-reading you posts I'd like to share a few items for your interest.
1- Consider a 6.2L F-350 or GM 3500. I left out the 6.4L due to the many literally hours I read MDS performance issues. (my own bias here)
Gas MPGs not the best but my 6.2l gets about 14-15 on the road which my Tundra never got!(15 mpg that is)
2- Here are some forums to come up to speed on the 6.7L Power Stroke and the I-6 Cummins.
2a-
6.7L Power Stroke Diesel - Ford Truck Enthusiasts Forums
2b-
https://www.cumminsforum.com/ &
DIESEL FORUM - ALL DIESEL FORUM &
https://www.ramforum.com/
There are quite a few emission items on these engines that takes a while to learn digest and grasp.There are Xcel spread sheets that show a break even point of 100k miles to make it worthwhile for the 8k to 9k premium on a diesel. Then there are extended warranties many buy with the diesel.
There is an investment of time to come up to speed on the new technology. Kindah keep in mind many of these folks love to modify, delete emissions, etc. Like many forums the majority of posts are problem related which can give a poor impression of a particular vehicle. (I know but the MDS just scared me away)
If you decide on a Ram either 6.4L gasser or the oil burner the best bar non pricing seems to be at:
New Ram 35 in Caldwell | Dennis Dillon Chrysler Dodge Jeep Ram
It took about 2-3 weeks of shopping to buy my F-250 6.2L to haul the NX and the 33' TT. So can appreciate your situation. If you do decide to get a replacement, used or new lots of folks have already suggested the Fluid Film treatment. I've never used it but from others it seems like that should be the first accessory, if you will, to make it your own.
Then many happy years of doing what you enjoy on your own time.