I used to have Bolle glasses with an RX insert - Eventually needed to change them as the glasses themselves started to fall to bits. Saw an advert for Tesco Opticians, and picked up a pair of basic sports glasses with RX inserts for £40 (special new store offer). Anyway, found that the sports glasses were poor optically, and it felt like I was 2 foot lower to the ground.
Not happy.
But, dug out a pair of Bolle safety glasses, and found the RX inserts fitted behind them. Right how to fix it in ? I used a small bit of wire that anchors to the bridge of the glasses and forms a small loop, I was able to then slot the inserts in with the loop acting like a clip and holding them in place over the nose bridge.
I can also swap the inserts with other tinted Bolle specs so long as I modify the specs with a loop.
The best seem to be Rudy Project, and they can cope with high prescriptions.
As these Oakleys will have a permanent bodge, can you fix the 'inserts' in with some wire (bent paperclip) - depends very much on the frame, and if there is anywhere to mount.