Moving Node: 802.11s Mesh Node vs. 802.11r Client

For a moving node, is "roaming" faster using an 802.11s mesh node or an 802.11r client?
I want to setup an AP on a vehicle moving in a tunnel, hardwired to a wi-fi client (or maybe 2 clients...) that connect to stationary APs at each end of the tunnel for backhaul (possibly using something like TP-Link CPE710 APs). I need the client to roam between the stationary APs as quickly as possible. I think I could do this fairly straightforwardly as a 5GHz mesh with a 2.4 GHz access point on the vehicle, but will there be a long roaming delay as the mesh re-configures itself? Will the node roam as soon as the connection speed is better with the other AP, or does it stay static until it loses connection completely?

I've seen similar topics about fast roaming vs. mesh but they just explain the difference between mesh and FT, not whether a mesh node can take advantage of 802.11r or equivalent.