Attempting to isolate Oxalic Acid from Barkeeper's Friend

I've recently gotten into crystal growing as a hobby and my current project is to try and grow Potassium Ferrioxalate crystals. However, I need Oxalic Acid for it, and it's not sold anywhere that I live.

Does anyone have any experience in isolating the Oxalic acid found in Barkeeper's Friend cleaner? All I really need is a few teaspoons of the stuff, but I can't find any guides online for this.

My thought process was to place BKF into water to dissolve the oxalic acid, filter the BKF, take the liquid and gently evaporate it, and allow any Oxalic acid to recrystallize out of solution. Does this sound viable?