That's actually the route I took. Not too expensive from Artech. I had a cheap concave board at the time (all my 'good' boards are convex ), so I just sanded it for a bit until I had about 1.5" perfectly flat area near the edges, put on a 1/87 tune via file, diamond, diamond finer, polishing stone, polishing stone finer. Totally geeked out over it. Looked like a perfect mirror.
Too bad it was my cheap foam board but cause its edges handled the icepack like nothing else. Actually got a lot of shocked stares, but that may be do to HBing itself. Did put a gash in my weak-side boot when I propped up my board when on the lift though. It's been in the closet since I bought my Donek Axis second hand.
My next buy will be concave or no sale.