Twenty years without a flat is good going.
Fyi the reason the back usually gets punctured is that the rolling front wheel flicks up a nail or whatever, which strikes the rear at just the right angle to poke through.
By sprays I take it you mean the aerosol foam – they should work but I can't recall it ever doing so for me, especially on a tube as opposed to TL.
Aerosols after used
after you get a flat and may have possible crashed.
Good thing with Slime and the like is they're supposed to work the moment the tube is punctured and may seal a puncture (complete with nail) before you even know you have one (though I'd be more confident of Slime working with tubeless tyres than inner tubes).
For the tenner it will cost you I would not hesitate to Slime your tyres.
Tubed or tubeless, I do it to all my bikes before a trip.
Because it can work unseen, it's worth checking your tyres once in a while to look for embedded nails.
A pump running off your battery is much better than CO2.
Airman Tour looks OK. You can probably strip off the casing to make it even smaller.
Underneath they're all the same.
I've used Cycle Pump for years.
Another suggestion is convert your (spoked?) wheels to run
tubeless tyres – much safer all round.
I just did this to my Himalayan (+ added Slime).