Should work fine. Here are a couple of mine so you have another data point. Using LuCI is the easiest way to do this, as it already knows about the MAC and other info, so you can just pick them from the menus on the Static Leases page when you do an "Add"...
config host
option name 'ubuntu-server'
option dns '1'
option mac '00:15:7E:BD:9B:B5'
option ip '10.1.1.200'
option hostid '0200'
option duid '00020000ac1d0ce49795f046f349'
config host
option name 'home-assistant'
option dns '1'
option mac '00:15:5D:01:A4:0E'
option ip '10.1.1.202'
option hostid '0202'
option duid '00049be8e4d00f32b053270b060705d70382'