By default, Map Sweepers does not support the use of custom playermodels, which is sorta a bummer considering Gmod's backbone is custom content, (though I do completely understand the dev's reasonings) however, there is a way to work around this through the use of other addons!

It's simple, you will just need "Enhanced Playermodel Selector" :
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2247755443

This addon allows you to open the playermodel selector through the console command "playermodel_selector". The addon overrides models that are applied by custom gamemodes, allowing you and others to see your custom playermodel!

However! You will likely notice that your c_hands are a bit, red and fleshy. This is due to Map Sweepers applying a filter over the c_hands which is intended for the default models, thus it'll look strange on your custom model, but fret not, there is a fix for this too!

All you need is "Need A Hand!":
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3347665507

By using the console command "nah_force_hands me" you will overwrite your c_hands with generated hands based on your worldmodel! (Also useful if you have a model that lacks c_hands, though it can create wonky ones otherwise). After this, simply enter a second command "nah_force_hands reset" which will revert your c_hands back to default and without Map Sweepers' red filter applied to them. You'll have to do this every run, but simply press the down arrow in the console to cycle through previously used commands.

With that, you can now sweep those maps in style! Get to it, J-Corp ain't paying you to loiter!