a planer on very dry old wood might splinter any area of odd grain, and rabbeting the back would leave you with that outside edge cracking off when you cinch down the skids .... if you have a real good planer with precise thickness control and real sharp blades it might work, but I'd be inclined to use the widest belt sander available

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot