@Stormkeep Thanks for the tip! But for me the issue was more that the wedding venue had to be something other than generic or it wouldn't show up on the list of choices, so I chose the something else that would come with free staff. Also bartenders at lounges and bars switch shifts at specific times, which was a handy time for having the ceremony while the guests didn't have the bar as a distraction.
If the new wedding venue lot requires us to pay for vendors like in a real wedding, I probably will just do so because my sims can generally afford it. And the new commands will hopefully fix the guests buying drink during the ceremony thing.
All that said, though, I would really like to be able to put food stalls in parks and have them staffed, so the mod might be good for me after all.