Didn't try low oxalate diet (although our son didn't really eat much veggies / nuts to have much oxalate in diet to begin with). Instead we focused on other potential sources including yeast and on ability to remove/minimize damage (calcium, magnesium, omega-3, probiotics, etc.).
Read this GPL article if you haven't already
Personally, I believe yeast/fungi is the main source (correlated to yeast markers), not much from food at least not for us.
It was one of the diets our biomed dr. had us try for DD as he's seen positive results with some of his patients. It didn't help us, but I'm a big believer in doing a trial since it's low-risk and potentially high reward.
Actually after reading more about it, yeast correlation may be secondary to the primary cause (which could be due to lack of beneficial bacteria such as O. formigenes that breakdown oxalates). That particular strain isn't available in probiotics but there are others that may be helpful in breaking down oxalates as well as reducing yeast.