Compressor relay switch
It has been a LONG time since I've worked with any of these, and most (refrigeration, then) compressors I dealt with were small enough not to use them..........
But why cant you remount your starter in a large enough box "if needed" and then find and overload that can be mounted "to an aside" and wire it in? I gather that the problem is finding one which physically fits.
The literal "think outside the box" LOL
Just a quik stab, along these lines?
https://us.rs-online.com/product/sq...ggDwbez04iSGPHmb8xrdl4GVU_JO1Eoe6WlUd0t7cv6FM