The one in the Coach Assist is for my Ventura submodel, David. Your Laguna could easily be slightly varied from that, but should be mostly the same. The 4th relay you may be able to identify by reading the printing on the wiring of the bottom row of relays, and comparing them to your printed legend, then add the additional one to your legend.
Printed sheets fade, especially in an outside environment, so after figuring out and verifying all your bay components and adjusting your printout, make a spare copy for your coach record file, then laminate the other to mount on the bay door or just keep in there. You can have Office Depot do it or, like me, use Avery’s 9”X12” Self Adhesive Laminating Sheets (10 Pack), product #73603.
As to your light issue, you may be looking in the wrong place. The electric bay we are talking about is for 12 volt chassis related components. You probably need to check the small 12v fuse box for porch light problems. On mine, it’s with the Multiplex modules and the 110v Main (50 amp) and Inverter (30 amp) boxes in the cabinet over the toilet. Check the fuse #7 in the black box; it can take some effort to pull its cover off for access.
Also, back on Coach Assist check my 2006 Wiring Diagrams book around pages 28-29 for Multiplex images to correlate with the photo below.
Joel