I thougth the Bilstein lift the truck 2.5" max? I know in my 07 Ram they only lifted the truck a little more then 2". Bilstein generalized the shocks and if you read carefully they say they vary between trucks. Just saying make sure exactly what it raised the truck so you can get the lift right after you ad the 6".
Yes changing the height on them is a pain since you have to take them totally out. I have a 6" lift in my 07 and I have the Bilsteins set to the max up front. Really when you want to do this just take the measurements as if you do not have the 6" instaled. The lift kits should make the trucks level, so it is different then the factory since the rear usually sits higher. So then you will hve to raise the rear a little more if the truck is level. With my truck I just had to add a block since the Fabtech kit I put on added a leaf to the leafs to raise the rear. In the new Rams they do not have leafs so I do not know how to do it with your truck. I would imagine you would use bigger coil springs and a spacer to get the most out of the rear. Just be careful adding more then it can take, you will sacrifice the ride quality. So if you put the Bilsteins to the max you will have to match the height lift to the rear as well. I think it will look great since you will be around a 8.5" lift. I guess you would be going with at least a 37" tire with this kinda height
The other option you have as well if you want to go big is adding a body lift. Having the Bilsteins up front is a great thing since the lift kits do not come with new shocks. So having heavy duty shocks up front helps control those big tires. I believe Rough Country sells a 1.25" body lift and Performance Accessories sells a 3" body lift. They actually look good, you do not see the frame and other B.S. Just a thought if the adding lift to the rear does not work.
I dont know if any of this helps or not, I just kinda rambled on hahah