I do something similar but using GRE since I don't need encryption. Then I have OSPF on the resulting overlay network (there are several sites) to deal with ISP

I do something similar but using GRE since I don't need encryption. Then I have OSPF on the resulting overlay network (there are several sites) to deal with ISP outages. One hop is via Starlink and that does use Wireguard because Elon likes to block tunnel packets but we gets through.