fair enough! hope you find a solution

maybe send out a google form that artists can sign up to that would be willing to be called on during the streams or events and commissioned art? that way you have a list of people that have time and already know you might be asking?

I dont know about the money problem but can you do temporary thumbnails? until the art is finished? these artists are very quick usually or if you know events ahead of time you can warn them so they can try and draw as the stream happens and ideas come?