Prickly Pear Pads for Large Part of Diet (Oxalates?)

I know prickly pear pads have an ok calciumhosphorus ratio (8:1 depending on the age) so obviously it is a bit high but I think it will help balance out dubia roaches and other vegetables. I live in england so collard greens and other commonly recommended staples are very hard for me to get fresh for a sustainable price. I found a good source of prickly pear pads so I'd love to be able to use it as a staple.
My concern is that I can't find the amount of oxalate in the pad apart from on a dry matter basis so I can't figure out if it is at a safe level. I'm also not sure how important oxalates are as collard greens and some other staples were much higher than I thought!
So basically if anyone feeds this to their Beardie this and has any idea on the level of oxalates I'd love if you could give me some info!
(Just an FYI I don't have a bearded dragon yet but I want to do my research before.)

As far as I know the prickly pear pads are a good staple - its on the nutrition website as a staple feeder
http://www.beautifuldragons.com/Nutrition.html ignore the kale thing its a good staple feeder
Karrie