"I almost thought about scrapping the nexus and getting a traditional derailer setup."
I think that might be preferable. I did a lot of work on the nexus at one time, and I really wanted to make an all Nexus red quality touring bike. In the end, spotting a rise in the Rohloff price I figured that was the way to go. I do think though that if you have the Premium Nexus, it can work fine without any of the stuff you mention. It will have a range that is narrower than normal, but it can span the what you need vs. want scale pretty well. I find I need the lower two rings on a triple most of the time, and am only missing a few high gear if I go to the 8, I would be willing to go that route, heck some people are touring on Pennyfarthings.
For me though, you are about even money to going for a derailleur at the moment when you price out a singulator or something, you could even possibly just swap a derailleur from a bike you already have. You will be giving back the main efficiency gain of the gearhub if you add in some kind of derailleur, You will loose the easy shifting in place feature if you add in a front gear and gain some chain suck as well.
I didn't get far enough to know whether you can eve use a blend of gears up front. You would have to look at whether you can legally go low enough on the front gears to get enough added range. Even the redoubtable Rohloff has front end gear limits.
Shimano does not even rate the red Nexus as strong enough for off-road, and similar concerns for hilly fully loaded. Many MTBers have tried it and I haven't heard of many problems, but I have heard universal concern over the earlier/cheaper version, as not being efficient or strong enough, so If you don't have the red I wouldn't even go down this path.
I would also want to be sure my set-up was simple to change tires on.
Overall, I'm not against the Nexus for normal touring use. I would just be a little more conservative about it than your current plan. There are other Nexus threads here search the forum.