I'm thinking along the same lines: Assigned starting times by bib range (units of 100 would make this easier, knowing that there will be a good 10-15% as no-starts). The only restriction being that I'd like all 1800 runners to be across the line by 7:30.
As for the first aid station, anything we do would help compared to having 1000 folks try and hit it all at once like in years past.
The start line coordination will be the critical factor. On paper, 20 waves, one per minute, sounds good. But organizing that is another matter.