I use the local UPS Store in Sacramento's mailbox as my permanent address. I did this specifically for my Dish Network to keep the Bay Area sports networks active wherever I go (Go A's!), and to show a home address Kaiser Healthcare Northern California accepts. I call or E-Mail FAX the UPS store about bi-weekly and have them forward my mail to General Delivery at whatever Post Office I am near. The mail usually gets there in 2 days, for about $6. The mailbox costs about $75 a year as I recall. I keep a credit card on file with them for mailing charges.
Kaiser has taken care of immediate healthcare needs in Oregon and Southern California, which are associated groups with my Kaiser Northern California plan. CalPers pays for my Kaiser as my wife's survivor, and I move to a plan pretty much different in name only next year when I turn 65, and combine the CalPers payment with Medicare. My drug refills are ordered over the phone, delivered to my UPS Store address, and forwarded on to me. I have used the USPS general delivery addresses for Amazon orders, too.