I'm thinking of rigging up a cable from the battery that would be accessible from somewhere underneath the seat cowl, which could then be connected to a trickle charger, without having to take the seat off everytime

Taking into account the need for a very securely insulated connector (to avoid short circuits due to water, etc)

Anyone set up something similar?

you mean like this?

optimate sell a premade one that allows easy connection of the battery tender when not using the bike.

Ha ha!

That's exactly what I had in my mind's eye

Thanks Neo