Quick update: Instead of doing the above, in the first instance I need to understand how 'bonding rr' works using two of the gigabit lans from the SH4. I happen to have a 'spare' barebones PC with an i7-8700 which I'll attempt to convert to a server. So I'll install a 4 gigabit lan card (Intel I350-T4 card with OpenBSD drivers) into it and run pfsense in a VM and attempt to bond the connection in that. If that's successful, I'll install a 10Gb lan card into the server and my main PC as well as (probably cat5e) cabling and do without WiFi complete (for now). I'll report back later in the week if I'm successful.