My Nomad began trembling as ‘Old School’ made his intentions clear!! 😂

One of the drawings at https://www.rohloff.de/en/service/handbook/oem shows that the end of the OEM axleplate is 32mm from the axle centre provided I have interpreted it correctly. How long is the dropout? The Rohloff guidance I noted previously shows that the worst torque condition is in bottom gear and the torque is backwards relative to the wheel rotation. This means that the force from the axleplate will be pushing upwards into the dropout assembly which looks quite strong. If in gears 12, 13 and 14 then the torque is in the opposite direction but is a much smaller force.

The Rohloff documentation somewhere gives a design loading which I concluded represented an overweight gorilla riding the bike (or maybe it's the tandem case with two strong riders?). I was happy to adopt a substandard solution on my Rohloff bike on the basis that I'm at the lighter end of the weight range. My opinion is therefore that this will work provided the support block remains in the dropout under all chain adjustment positions and you don't weigh 140kg. Given that the chain length can be adjusted in increments of 1" (25.4mm) unless using a half link, it might be necessary to choose the chainring / sprocket combination which provides the required gearing while keeping the axle close to the back of the dropout.

Bullet cam https://www.chilli-tech.com/action-cameras? The new version has the option for a cable to an external battery but doesn't mention the limit to the size of the memory card if wanting to record all day. I tried one of the older bullet cams which made me realise how much I wobbled from side to side when pedalling! I suspect that the image stabilisation on the more expensive of the new models doesn't compensate for wobble.

I can't recommend specific editing software. I would start with whatever is available for free and see if it does the job. If not, this exercise helps getting to know what features are needed in any paid-for software.

Have you purchased the Trickstuff Exzentriker?  I’ve not seen one in the flesh but it looks as though it comes with the bearings pre-installed in the eccentrics. External bearings seem to be more susceptible to water ingress than the internal bearings of conventional square taper cartridges; I trust that the bearings are both well sealed and easily replaceable.

Given also that the bearing housing is designed to thread into a standard BSA BB (1.37in X 24TPI), and the male threaded inserts will further reduce this diameter, there cannot be a great deal of adjustment to move the 24mm crank spindle backwards or forwards. Presumably you will need to use half links, or am I missing something.

It also seems that the drive side and non drive side eccentrics are independently adjustable. How do you ensure that the two bearings are concentic and the crank spindle is perpendicular to the vertical plane of the bicycle? 

All in all, it look to me to be a solution to a problem that could be solved more easily and more cheaply by other means. Is there any reason why you cannot use a chain tensioner?

Any MTB crankset will be fine, the outer positions on doubles and triples is almost identical. You can always push it out another mm or two with the washers that come with the hub.
I like mine perfect, with ST cranks, chainring washers and BB washers and an EBB that can be run a bit off center it's always possible.  A bit of a faff, but do it once and always replace like with like and it on;y needs doing once.  I've a feeling Rohloff have relaxed their attitude to chainline, I recall them making a bigger thing about it's importance.