Sorry, I thought the only difference for level I was this.
US1.1.5.1 Level I matches are not required to comply strictly with the
freestyle requirements or round count limitations.
And for your fix for Level II and higher, I don't think you can mix Classic and Metric targets in the same stage.
4.2.1 There are two types of paper targets approved for use in IPSC
Handgun matches (see Appendix B ). These types must not be
included together in any stage.
My point in this discusion is not to get under anyones skin, but to answer the question " Is there a written standard foer this for a USPSA match?", and to voice that in my opinion clubs that run USPSA matches (whether they be 3-gun or pistol) should adhere to the USPSA rule book when designing stages.