Any thoughts on doing that with the original wasteboard?
I did this for probably a year before upgrading my wasteboard. The one downside is you will create a ledge since you cannot plane the entire thing. You will create a pocket in your waste board.
Works good if you intend to stay within that area, but not so much when you have a larger piece as you will need to prop it up.
What I do is fix a second board on top of the original board then surface that one. You can make the second the size you need and plane all the way to the edge.
I make a top layer for the waste board out of 1/4" or 1/2" MDF and I mill out the clamp screw holes using the project someone posted in Easel. I like to make the holes slightly larger than what the project calls for.
I then use a medium tack spray adhesive to stick it on top of the original waste board. I use 4 screws with the heads cut off to align the original and new wasteboards so all the screw holes line up.
When the top board needs to be replaced it can be peeled off and a new one can be put back on.
Do you have this project on hand? Seems silly that Inventables doesn’t have a premade one.