It doesn't have to be all that hard. We set up virtually every bill to be automatically charged to a credit card or to a checking account. I think we had one single bill (oddly enough, the boat insurance) that had to be paid by a physical check. After awhile it didn't matter if we ever got our 'mail' forwarded to us so it became pretty insignificant and for the most part we live that way now, ashore. All you have to do is get online occasionally to check on things and set up your credit card to be paid and even that can be set up automatically.
More generally, if you are realsitic as to what to expect, and have a willing partner, you can certainly make long distance cruising a part of your life. There are obstacles, and our western civilization tends to put up a lot of roadblocks ... But if it's important enough to your life's goals there is no reason not to head out.
Max