ironchefmitty , Dellajoy - The trick will be to buy gessoed Belgian linen canvas in rolls (Amazon will help with brands and grain of roughness), buy few stretchers and special pliers to stretch canvas. (Videos how to do that are available on youtube). After painting is dry it can be removed from stretcher, gently rolled and saved for storage or shipping. Also if you use Belgian linen you can use tape or staples to attach it to the plywood and paint on it. It will resemble panel somewhat.
PS Belgian linen refers to a place of manufacture the linen textile. Final gessoing can be done in Italy, Belgium, USA, etc. This is the top quality canvas.