If you don’t fancy cutting the insulation tape to width, try Trimline tape, available in many colours and hopefully has the right width on the roll.
I have used for lining my 16mm/foot garden railway locos, it can even form curved lining
https://www.cornwallmodelboats.co.uk/acatalog/Model-Technics-Trimline-Black-P5523672.html#SID=844