Like you, I’ve no centre-stand, at home I sometimes use a paddock stand, otherwise, and when away for any time, I use my ‘bespoke’ home-made chain oiling system and stand..
In other words, I carry a small bottle of engine oil, an old toothbrush, and a piece of wood.
I lean the bike over a little onto the side stand, just enough so the rear wheel can spin, chock the swing arm near the axle on the opposite side with a suitably cut batten of wood (this is admittedly easier with an assistant but is not difficult alone), then dip the toothbrush in the bottle and oil the chain as required.
Works a treat, and importantly, costs bugger all.
Though I think at some point, I’ll knock up a bulb-oiler as described by Rich.