I would also prefer this approach, but note that for IV there are various caveats one should keep in mind. See eg
@article{lopes2014bayesian,
title={Bayesian instrumental variables: priors and likelihoods},
author={Lopes, Hedibert F and Polson, Nicholas G},
journal={Econometric Reviews},
volume={33},
number={1-4},
pages={100--121},
year={2014},
publisher={Taylor \& Francis}
}