With the new Citadel 0.3.5, available for Raspberry Pi, DTV Electronics, and Nabi devices, Bitcoin Knots comes pre-installed by default.
It features a datacarriersize=83 by default (as in Core), and you can, of course, change it to 42 by modifying the file in home/citadel/citadel/templates/bitcoin-sample.conf.
On the first run, the user is prompted to run Core or Knots and can switch between the two later at any time.