The latest OctoPi release with the latest OctoPrint already included and RaspiWiFi pre-installed.
This repository automatically updates the OctoPrint installation on the latest OctoPi image and provides the resulting image ready to flash. Checkout the releases.
A simple update script is run via CustoPiZer.
All that is done is running the equivalent of pip install -U OctoPrint==<latest version>.
Sure, check out CustoPiZer's README for instructions on how to set up your own image build for modified but clean OctoPi images!