All options passed my brain, haven't picked one yet...
The device claims to be "pumped" but actually it isn't, not really. It has a diaphragm chamber with non return valves, and it relies on the pressure pulses of the exhaust gas to make that membrane oscillate. The clicking noise indicates positive gasflow to the measuring cell. But the thing definitely needs something.

So most likely I will make something like a small T where the feed from the engine is opposite to the line towards the device, so the pressure pulses directly hit that "pump" thingy. Should not be too hard. More like it needs to be dimensioned such that I can hook up a great variety of different engine sizes.

I'll figure something out.

In all fairness, I expect the aero engines to run pretty decent. I more hope to be able to get some sort of "baseline measurements" from that, that possibly would allow to for example set curves such that CO levels remain by and large constant over the entire throttle range. But honestly, I first have to learn what kind of CO levels these engines feel happy with.

I don't expect needing one to set up my engines, but it COULD be that I will be able to provide additional info. I have seen a few people now that for one reason or another never managed to develop the "ear" to tune an engine. Perhaps for those it can be of help to figure out how to set up a fuel curve using this or a similar device.
It's not a cheap device, but also not prohibitive expensive. I don't know what these things cost in the US, I paid about 200 Euro. Fair bit of money, but I am going to use it on the Ducati as well, so I figured it was worth the money anyway.