wing tank fuel gauge

Well, I did a little more research. I apparently have the stainless tanks that replaced the original ternplate tanks. The ternplate tanks had a sight tube gauge in the right tank, but it was not accurate. The stainless replacement tanks didn't have gauges, and many still fly without wing tank gauges. Their gauge is their watch, which is probably just as accurate as an actual gauge. I will use my watch, too. And keep an eye on the header tank wire.

I recently purchased a 415c. It has no fuel gauge for the wing tanks. The tanks do not extend into the fuselage so the pilot side float gauge in the tank top is not an option. Any suggestions?