You could make up a short lead with the KTM bullet/spade connectors to accessory socket (after finding out if its bullet or spade)
The headlight cowl is very simple to remove, on a couple of elastic bands.
When you get the hire bike, remove the cowl, plug in to acc1 or acc2, then leave the accessory socket in behind the cowl.
Remove when you return the bike.
In fact, thats how I ran the SatNav on my 690 anyway.
Regards
Dazlove