There is long term parking in PV, below are the rates in pesos;
1 month 1300
6 months 7200
Daily it is 45 - 80 depending on how many days, day 1 is 80 day 29 is 45
They are located directly under the pedestrian walkway at the aeropuerto, phone number is 322-221-2750
Probably not worth it if your gone for 6 months at a stretch but for those quick trips ..
Rick