Road signs do not really make good skid plates, not heavy enough at all, what they do make is a way to keep dirt,sand etc from entering the front skid since it is shaped like a shovel and scoops eveything up.
I'll throw some pics up in a few
There are four bolts in the bottom of the support below the radiator, you can use those plus drill into the front skid to support it. On mine since I have the ARB I attached it from the front of it all the way back down. I curved it just so I could have more clearance when pulling up and getting ready to climb rocks or whatever. It does a great job and keeping the junk out of the front skid. Also I just made it as wide as the front skid.
These are all old pics but if you need more let me know



