I farmed this a bit on live. I'm not sure how valuable farming Skyshrine is over here relatively speaking. The big ticket drops from wyverns on live were the weapons (Lath Drinor and Skyfury Scimitar) which probably aren't going to be worth dogshit here. However, Elder's Earring, Square Helm (graphic), and Oiled Greaves might be fetch a decent tag. In addition, Wurm Lord's Shawl is very solid for the caster farming these.
Anyhow, the level 35-40 cubes before the Vehlics had drops from the Wyvern table, but the rate might make them not worth farming.
I would suggest doing this spot:
https://www.youtube.com/watch?v=8uiGMsKmMh8#t=11m13s
Nothing should see-invis up to this point, so it's pretty easy to get to. You should be able to clear those 4 Wyverns without a problem. Hopefully they're not too MR on Project1999. You can either keep Jaelk cleared and kite backwards or just kite in the room and monitor respawn times.