You can work around this by using Opt.Transitions = [1 2]. This will tell saffron to only use the transition between levels 1 and 2 (the lowest Kramers doublet) and skip all the other transitions.
In order for this to work properly, please download the latest version 5.0.16, which just posted.
In the current version, there is no way of specifying the temperature.
However, there is a workaround: Use Opt.Transitions to specify the transitions between the electron manifolds you want to be included in the ESEEM simulation. In your case: Opt.Transitions = [1 2].