Battery Issue 2008 V10

I've been away from home for quite sometime and my battery is drained. The ignition will not release the key, trucks in the garage so not a huge deal, but what is the best way to charge the battery? Is there an under hood connection or do I have to move the front seat to get under for the accessory battery, or do I need to get to the spare and get the rear battery? I'm looking to do this as painlessly as possible.

Also, since I travel quite a bit where is the best place to hook a battery tender, would that be under the hood or somewhere else?

Cheers.