Sanity check - is it OK to use giant subnets (i.e. /16) for public WiFi?

I am working on a temporary network to provide public wifi at a golf event.

We are working with Cisco who are providing approx 100 Meraki APs and a pair of wireless engineers to set them up. My org is responsible for providing the underlying network connectivity.

We expect we will see an absolute max of approx 15k clients connect concurrently - realistically I expect this number will probably be more like 5-8k.

The physical area we are covering is split across the golf course - there are about 6 large temporary tent structures set up on the golf course which will each have multiple APs. There is some separation between the areas (ranging from about 300' to 1500'). The entire golf course is very open and centralized, so you can see from one side to the other. We do expect that clients will move between areas, but don't expect that we will have people congregating between the main areas.

My original intent was to set up a VLAN / subnet for each tent, but the Meraki folks are advising us to create a smaller # of VLANs, or even to consider doing everything as a flat network because keeping client devices on the same subnet aids in a smooth roaming experience. Their advice was to limit each VLAN to about 10k devices.

I can certainly create 1 or 2 giant VLANs, but my kneejerk reaction is that is way, way too many hosts in a single broadcast domain. However, since these guys work for Cisco and do this sort of thing for a living, I am inclined to trust that they know what they're talking about. And admittedly, most of what I learned about subnetting and planning networks was learned 20 years ago, so maybe things have changed.

Still, it makes me nervous, so I am hoping the community can sanity check this for me.

All of the APs will be on a common Cisco wired network with redundant 10 Gb/s links between switches, in case that matters.

TIA!