Personally, I prefer to size the tanks such that they do not exceed the 80-psi under worst case scenarios. Varying the pressure causes stress on things, including your WH tank, and things like washing machine hoses. The porcelain lining doesn't like it when it gets stressed. The WH is tested to 300psi, so won't burst, but that doesn't mean repeated stress to the lining can handle it. A bigger ET is cheap compared to replacing a WH earlier than needed.
A bypass PRV is mostly a waste of money and one more thing that can fail today, especially if you have that high of inlet pressure. The bypass can only open when the house side exceeds the supply. If it got to 150psi, the WH's TPR will open, or at least should. Plus, most utilities either now have, or will be installing check valves, so there's no place for that bypassed valve to let water go, either.
The more an ET bladder stretches, the shorter its lifespan. The tank manufacturers don't particularly care as long as it makes it through the warranty period.
Do what you want, upsizing the tank is cheap all around. ONe leaking WM hose could cost thousands.