I have a double crankset, run a bashguard/chainguard in the outer position, the chainring in the inner position.

The plan is if I go somewhere with massive hill climbing, install both the 36t and 44t onto the crank (with no bashguard) before I leave home. No tensioner. If I am going to be climbing substantial hills for hours, then in preparation the evening before, remove a section of chain and move the chain over to the 36t from the 44t, readjust the eccentric. Have two quick links installed on the chain to make this an easy change. I do not want a tensioner or front derailleur, the less hardware and fewer things that can go wrong, the better.

I picked 44t chainring for normal around-home use, that puts my gearing in about the same range of gearing that I have on my derailleur touring bikes. I use gear 1 and gear 14 with about the same frequency, so that appears to be just about right.

For sizing the smaller chainring, I figured out what my slowest speed was that I could stay upright. I then calculated what chainring I would need to give me that speed with a cadence of about 72, which is the lowest cadence that I like to run. The result is a 36t chainring with 16t rear cog. I tried this combination, it allowed me to climb at a very low speed with comfortable cadence, but I really missed the higher gears, thus the 36t chainring would be used only for those days with a lot of climbing when I need the lowest possible gearing.

Chainline is not perfect, the chainline would be just right if I put the chainring in the outer position. But, it is close enough and I am not going to obsess over it. I intentionally chose a shorter spindle than would have been ideal for chainline because I wanted the Q factor on my Rohloff bike to be similar to my other bikes.