Not sure if this is what you need, but if you want a website blocker that is always tuned on, you could try "Cold Turky Blocker". It is an external app that closes the browser when you disable the web blocking extension. It is hard to delete if the blocking is active. It also blocks other browsers. You can set requirements to change the block-list for example like "only at 4am" , " "in 1 week". Theres a free and a payed version. Lately it makes opera crash about twice a day, but it is sill worth it. And maybe it will work better for you.
