That's a good question. Here's a definition of "fair" aimed at UDT-type thought experiments:

The agent has to know what thought experiment they are in as background knowledge, so the universe can only predict their counterfactual actions in situations that are in that thought experiment, and where the agent still has the knowledge of being in the thought experiment.

This disallows my anti-oneboxer setup here: http://lesswrong.com/lw/hqs/why_do_theists_undergrads_and_less_wrongers_favor/97ak (because the predictor is predicting what decision would be made if the agent knew they were in Newcomb's problem, not what decision would be made if the agent knew they were in the anti-oneboxer experiment) but still allows Newcomb's problem, including the transparent box variation, and Parfit's Hitchhiker.

I don't think much argument is required to show Newcomb's problem is fair by this definition, the argument would be about deciding to use this definition of fair, rather than one that favours CDT, or one that favours EDT.