One thing you could do is use a multimeter to check continuity on that wire. Pull the fuse out of the suspected circuit then measure between the fuse box output contact and the wire.
Make sure the wire doesn't read 12V at that point, so you know you have the right fuse pulled and aren't just measuring between a different circuit and getting continuity because both are still connected to the battery.
Something else you can do is turn on everything (that you'd ever use at once) on that circuit and measure current across the fuse box contacts to see how much margin the circuit has to power something additional. In some cases if the wire hasn't been downsized you might be able to put a little larger fuse in to compensate (consult a wire gauge vs current chart) though it goes against the design intentions of providing more protection by blowing sooner if anything is using more current than it should.
If the tap doesn't need to turn off with ignition, I'd probably just tap into the lighter outlet or auxiliary faux-ligher outlet as they are 25A/20A respectively (may vary by model year) without nothing else on their circuits AFAIK. The rear blower motor appears to have only a 7.5A fuse.
Heh, I didn't answer your question. There is another rear control panel circuit that takes a 7.5A fuse... guess I'm not going to answer your question, sure seems like that wire bundle would be for everything in the rear console.
Some vehicles with the exterior
lamp out indicator/feature would have a sensor box with the light circuit wiring there.
