@fry_p Excellent job. What you posted is exactly what I would have had you do.
Just keep in mind that this is only likely to work with the exact sub-model, the one you said: Surface Pro 4 1724
For future readers, all that’s needed to make a vendor class for other sub models is a packet capture posted here on the forums, or analyzed by yourself. Simply look at the device’s DHCP Discover packet, inside option 60 you’ll find the vendor class identifier.