At some point, most of us find benefit from having installed two additional shutoff valves, one each for tank. Agreed that they're superfluous 99.9% of the time, but:
1) if the airplane is parked one wing-down, fuel will crossfeed and overflow the low tank's vent, and
2) calibrating the sight gauges with crossfeeding is difficult, and
3) maintenance of one tank requires de-fueling both tanks (plus, one tank can be used for temp storage of fuel from the other if there are shutoff valves),
4) roll trim can be provided by unbalancing the tanks (but this violates redundancy, so I'm not cray about the idea except in special cases), and
5) you can get home even with one leaking tank.

Note that I am a proponent of feeding from both tanks all the time in flight for lots of reasons and only turning them off in unusual cases. A header tank is also marvelous.

My Kitfox fuel system is not pretty, but fuel always goes downhill (except where it travels along the floorboard but is still guaranteed to be pressurized by the header tank).

I also used nylon fittings, but after about 15 years, they'd shrunk to the point that the only thing keeping fuel from leaking was the (very excellent) Dow 730 sealant. No credit goes to me for missing this issue for at least a year or two.