Bwahahahahaha! Come on over to my place and I'll put you to work taking the 35 screws out of the Tupperware on my RT. The KLR is still one of the easiest bikes to work on.
There are no aux circuits to use, unfortunately. The least destructive thing you can do, and you might want to consider this as an improvement over your current situation, is to tap off of the horn circuit right at the horn, which is behind the coolant overflow tank. You can use a 1/4" spade tap
or cut the existing connector off and crimp a new one in place with the tap wire coming out of it.
Better still is to build an aux fuse box (the one you found under the seat is all there is, save for the main fuse down by the starter relay). This is one of the slickest fuse boxes I have found and Joe is a great person to deal with: ATC/ATO 5 Circuit Bussed Fuse Box
Cycle Terminal (Joe) has all the connectors, tools, and accessories you could ever need, too. I've been doing business with him for a long time and have never been disappointed.
If you build an accessory fuse box, a good location is under the left side cover near where the vapor recovery canister was (after you take it off and carefully store it away in case fascists come to political power and insist on motorcycle emissions inspections) and a good source of power is the starter relay, as it is nearby and easier than coming off the battery positive post.
There are other options, such as the FuzeBlocks FZ-1, Centech AP-2, or Eastern Beaver's PC8 (I have one of those on my RT, quite satisfactory).
If you are interested in pictures of the Suzuki box installed on the KLR, say the word and I take a couple of pictures.