...It looks like I can't reserve my home week online for next year until I pay, but don't really want to pay if they aren't due yet.
Actually, your "home week" unit is reserved for you up until exactly 6 months prior to the first day of the owned week. If you use your points in some other way resulting in taking away some of the points associated with that home week, the HRPP reservation is in jeopardy. In any case, if you want to confirm usage of all or part of the HRPP unit, you need to call Hyatt for that confirmation.
It is true however, that from the time next years invoice is sent out, you are restricted in on-line activity until the MFs are paid. I never have understood that policy as the MFs are not even due until a specified date. The member is still in good standing so why limit his or her activities?