A cruise simply cannot be too long for me. The longest we've taken so far has been 47 days from Fremantle around the Indian Ocean to South Africa and return. Could have easily stayed on board twice as long.
In terms of the boring necessary admin:
We usually get a town car from home to the Port and pre-arrange for something similar to pick us up at the conclusion of our trip, whether that be to the same port of a return via air. If we're in a situation where we leave and return via air in order to reach our embarkation Port, we'd drive to the airport and leave our car in the long term parking which costs $99 for each 30 days.
Our mail is picked up and by a neighbour and our bills are paid via direct debit.
We live in a secure apartment block with any maintenance arranged via the Strata therefore, no impost on individual owners.
We don't have pets so that's not something which we need to make arrangements for.
Voila, stress free long term travel!