My eventual solution was to use an AddrLink ipeps device, which kinda sorta provides KVM over IP.

The problem is, it's interpreting the VGA signal to try to locate the cursor, and this detection is suboptimal, which results in a frustrating mousing experience. It's OK for just investigating something, but it's not terribly practical for actual regular use of the machine, unfortunately.

We need an 030 PDS/Nubus card that provides modern KVM/IP functionality!