I take it you want to retain the looks of the stock wheel? Depending on what the wheel is constructed off I would think a home built wheel would be hard to pull off....and still look decent. At 18" it sounds like an old timer, can you post a picture of it?
As a side note and as a retired Police ofcr. ....not from Texas mind you, I never heard of a smaller steering wheel infraction. I did cite a guy once for unsafe veh. section driving (???) his car with no steering wheel but had a pair of vise grips on his shaft. Made him park it until a tow rig came and picked it up.