Zerotier + sshfs is something I use consistently in similar situations to yours - and yes, zerotier is similar to a vpn. Using it for a constant network connection makes it less critical to have everything mirrored locally. . . But I guess this doesn't solve your speed issue.
I"m not an expert in rclone. I use it for connecting to various cloud drives and have occasionally used it for an alternative to sshfs. I"ve used vfs-cache for cloud syncs but not quite in the manner you are trying. I do see there is a vfs cache read-ahead option that might he|p? Agreed on the documentation, sometimes their forum helps.
zerotier + rclone sftp/scp mount w/ vfs cache? I haven't tried using vfs cache with anything other than a cloud mount but it may be worth looking at. rclone mounts work just as well as sshfs; zerotier eliminates network issues
I can't find my notes on how I got this to work on Debian 11 but, if I recall correctly, I had to disable NetworkManager and setup networking directly via /etc/network/interfaces. I no longer have Debian running but at the time this worked for me:
source /etc/network/interfaces.d/*
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
# allow-hotplug eno1
auto br0
iface br0 inet dhcp
bridge_ports eno1
I'd add:
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