Gauge thickness is only a good (necessary) installation consideration. The off control at the key is your problem to the time meter. Although discussions run for and against an ammeter, I personally like them. To me they are like an oil pressure gauge which is "dynamic" in that it shows movement (and strength) of current flow and direction while voltage is static although also useful. Break the tie and install both. I have found the JC Whitney sourced Taiwan gauges very good , but good combo setups are available at auto parts stores.
My Craftsman ammeter lets me see the heavy charging rate just after starting and then a lighter rate while running before starting again. Negative needle can tip you to battery charging problems. Use good crimp joints on the terminals, or better, solder , and use shrink tubing readily available. route carefully and tie up long runs.:thumbsup:
Edit. There are digital gauges which are very "trick," but I guess you probably have an analog type with needle pointer, The led style need a shunt I think, which should come in the kt.