I have a need (long story) to use a long strip of 3/8" plywood under a door casing vertical piece and I plan for it to be slightly wider than the casing. It is joining old lathe and plaster and, for a long and irrelevant set of reasons (I must mention this because I know how some of you like to challenge principal designs), I cannot use drywall.
So if I have about an inch of plywood sticking under door casing, will it be possible (meaning adhere and look like) drywall? I know that it's possible to mud over plaster to iron out uneven spots but not sure if it works when applied over plywood.