To try to address these sorts of models, the best way in my opinion is to write down the math of the generative process. You have:
- The base probability (and its logodds) logit(p_{base})
- The error \varepsilon.
- The prem.
Your generative process will look like this:
\varepsilon \sim Normal(0, 0.2)\\
prem \sim Uniform(-2, 2)\\
Outcome \sim Bernoulli(expit(\varepsilon + prem + logit(p_{base})))
However, you have to be aware that it will be hard if not impossible to distinguish between the effects of \varepsilon and prem (the parameters might be unidentifiable)