JCDave wrote

[...] line-of-sight cannot be established to a single Root AP.

As @shberge said, you can have multiple root APs.

Let me add three more remarks you should keep in mind:

1. The characteristic of a mesh network is that not all mesh APs need a free LoS to the root AP. Typically, mesh APs are linked with the nearest neighbor (their uplink AP), which not necessarily needs to be the root AP. Only uplink APs in the 1st hop (up to four, see 2.) need a free LoS to the root AP.
2. Each AP can feed up to four more mesh APs in the same hop. You can have three hops at maximum.
3. A mesh network will not aim at extending the wireless network's client capacity. The mesh was primarily designed to extend the WiFi coverage and to simplify EAP deployment.

This means you should use mutiple root APs anyway if you plan to support an extended client capacity of the network on the campus.

@JCDave for a PtP link you cannot use a mesh with two root APs.

But you could use a root AP ↔ mesh AP 1st hop ↔ mesh AP 2nd hop ↔ mesh AP 3rd hop setup. Unlike in other mesh concepts, in Omada mesh networks a mesh AP always has exactly one active (linked to) uplink AP, albeit the mesh can re-configure the uplink AP to use if the original uplink AP should fail.

JCDave wrote

I just didn't know if it was possible to replicate that same configuration more than once within a given LAN.

Why not? It's just a plain AP of which you can have plenty in the same LAN, thus it's not a Root AP until a Mesh AP connects to it.

Let's be more precise. An EAP becomes a so-called Root AP only if:

• it is wired to the network and can reach the router/Internet (you can set the IP address it should use to test for upstream connectivity),
• it has at least one other EAP linked to it wirelessly, thus becoming the uplink for this linked EAP.

But now, I realize that every wired mesh-capable AP can function as a Root AP

That's correct. A wired EAP can become a Root AP, but it's not just the cable connection what makes an EAP a Root AP.

For example, see the following topology which (ab)uses the meshnet as a PtP link:

EAP 1 is the Root AP wired to the LAN. EAP 2 is wired, too, but to a laptop. Despite both APs are wired, EAP 2 is still a Mesh AP wirelessly linked to the Root AP.

You don't even need ESSIDs for the APs. For meshing they will choose a 5 GHz WiFi channel with a hidden ESSID anyway (using the BSSID); in my test setup below it is channel 36:

@RavenKnight, by adding more (wired) EAP225-Outdoors. There is no other way to increase the user capacity of an AP.