2nd battery hook up

I have a 2007 Suburban.  I'd like to hook up the 2nd battery in parallel.  But the battery trays are located at far corners.  Does anyone know if there is an easy way to install the 2nd battery?  ...or do they expect you to just store it there as a spare?  Thx.

go buy some 4 or 2 gauge wire long enough to connect the 2 batteries together at your local radio shop

I just connect the pos. of each battery together and the neg. from the 2nd. to the eng.

Easy enough--that makes sense.  I guess I was wondering if there was any pre-installed or pre-wired connections near the 2nd tray.  But it doesn't sound like it, and this is a super easy solution.
 
Thanks.