https://www.pinterest.com/pin/369717450643003231/
This poster was likely also by Wilfred Jackson, for instance. His thin off model Mickey proportions match up well here.

This actually looks to be a Les Clark piece; new information has surfaced showing that the promotional materials of Mickey playing the mandolin and him tipping his hat were by Clark; and this piece I linked is more similar to those two than any of Wilfred Jackson's work....

If this is in fact a Clark piece, the model consistency appears to have been way off because Mickey's buttons change shape from circles to ovals and become spread out quick if you look at the other art of him tipping his hat! Oh, and Les making Mickey slender isn't unusual; he even does it in 'The Birthday Party' as an example. Mickey before 1931 was off the charts with model policies not being strictly forced.

Even after the model sheets came, I still found him off model in various places before the middle of the black and white United Artists runs....