Is the following setup code and/or recommended?

82 psi.........................50 psi............................................... ............
meter=shutoff==filter==PRV===shutoff============== waterheater
.....................|.....................|...... ................|.............|...........|....... ...
.....................|.....................|...... ................|.............|...........|....... ...
..................sillcock ..........pressure ............exp.........cold......hot.....
.........................................gauge.... ...........tank........water...water....

(Plus addiitonal shutoff valves?)

filter - whole house carbon block filter, which reduces pressure as it ages
PRV - pressure reducing valve (required by code - Michigan, 2009 IRC)
exp. tank - expansion tank (required by code)

Is it code to put the sillcock and water filter before the PRV?

We want to measure incoming pressure at the sillcock rather than installing a second pressure gauge before the PRV, and to protect rubber parts in the expansion tank and keep sediment out of the PRV by filtering before them (as well as removing chlorine from inside water).

The inspector says PRV is required by code even if incoming pressure is 80 psi.

What is the standard setup and why?
We are Owner builders/architects.