If your ratchet strap slot proves to be difficult to cut, you could also drill a slightly larger hole than Jon did and use a "rope ratchet." (If you type those and add .com, you can see what they look like.) You can buy them at most big box building supply stores.
I use them all the time for securing things in my truck or to a trailer. They are not as cheap as Harbor Freight ratchet straps, but last a LONG time and are very convenient.
Just thought this was a possibility worth mentioning...