I’m a venue manager. If Trump’s team wanted to organize a rally at my venue, (and I was forced to allow it), I would require 100% payment in full before they were allowed in the building.
In fact, my building collects a refundable cleaning/damage deposit, and I would intentionally over-estimate everything about the event; We estimate the event costs and require clients to pay up front. Then any overages can be claimed from that deposit, or invoiced after the event. Equipment costs, labor needs, room rental times, catering commission, merch commission, etc…
I would intentionally over-estimate all of that. So when they inevitably have some overages, (like maybe they use more mics than expected, or maybe they show up two hours early), those are already paid for in their initial payment. Then I’d just return any unused overages with the deposit, which is SOP. Because I know that if I had unbudgeted overages and tried to invoice after the fact, I’d never see a single cent.