For stealth tuning, I just found out about this:
2011 - 2015 Ford 6.7L Ag Diesel Solutions Truck Edition Performance Module 22200 - 5 Star Tuning
I use 5-Star's SCT based Daily Tow for much improved driving, but in case of a major failure, it can be detected by Ford. The product above doesn't write to the PCM so it should be undetectable once removed, but I have no idea as to its effectiveness.
As far as additives go, everyone who uses them has their favorites. Not only can you improve lubricity for longer fuel system life, but cetane boosters should help reduce soot and regens. I started with Opti-Lube Summer as the Opti-Lube XPD, Summer and Winter were top performers in the only study we know about from 2007. Right after getting a gallon jug of the Summer Plus, I found out about Archoil products and started adding AR6200 to my diesel fuel which improved my mileage between .5 and 1 mpg. I get the best results using the minimum dose of OL with the AR6200. At a minimum, I suggest Motorcraft PM-22A.
There have been a few suggestions that Valvoline Premium Blue Extreme 5w40 (NAPA) helps reduce regens, but I haven't tried it yet. After running Rotella T6 for 15,000 miles, the dealer mistakenly put Motorcraft 10W30 in and it seems to be working fine with the AR9100 oil additive. My regen frequency is the best yet at between 500-600 miles, mostly highway.
Don't change the factory oil or use any oil additives until 5000 miles to allow proper break in. Keep the RPMS up by locking out 6th gear for speeds below 50 or by using Tow/Haul mode. That keeps from lugging the engine at 800-900 rpm during break in.