... a match? cigarette lighter? LOL
as for the tender, seems like a week on the Ape and then a week on the Kymco sounds like a workable plan with only one tender. You can get multi-battery tenders but I think the price is much higher.
I have this huge ex-Uhaul diesel truck that has 2 monstrous big giant batteries. I used my 1.5 amp schumacher motorcycle "battery maintainer" to charge these batteries together when they were too drained to crank the truck. Took about a week, but got them charged. And the little yellow light turned green after this week of charging, so that means it was done and wasn't over-charging right? Which means the "protection circuit" wasn't goofed by having 2 batteries on at once, right?
So, what if you put a set of jumper cables from one bike to the other, and kept them both going at the same time? Brain is stalled, so someone would have to inform as to which end of what wire would go where... but I don't see why it wouldn't work. (Just don't hook it in series, as that would make 24v and blow up the charger.)