I have a Pro Tools subscription and experience with the platform.
Unfortunately Dante Via is not the product you need. It is limited to 16x16 channels.
Virtual Soundcard can do 64x64, but I'm not sure how you would route the inputs from the console to DVS dante outputs that can be picked up by another computer.
It would be much cheaper to buy a splitter and a simple analog console (Or cheap digital) and do the broadcast mix on that. Split the inputs either at the stage or at the console then run a copper snake to some other room where you can have a desk and some cheapish studio monitors. You would need an assortment of comps gates and maybe a reverb or two. Or you could buy another persons desk. Maybe a used one. I only suggest that because ya'll would already be used to the presonus workflow.
Another option is to stop using VIA to bring in inputs to the desk over USB. Bring those into the desk via analog signals. Maybe through a sub mixer. That frees up the USB port for another computer which can run your choose of DAW with which you could use for a broadcast mixer.