I just booked a flight to TLV for February. When I did the cost comparison, a B fare was only slightly more expensive than the cheapest Y fare + co-pays, and a B fare earns me 150% RDM's + EQM's. I was also able to confirm all 4 upgrades at the time of booking.

I would suggest that you play around with different fare classes + co-pays. You do not state your status level, but you might actually be better off buying a B fare if you can confirm the upgrades at the time of booking. If not, the cheapest fare + co-pay probably makes more sense, since the co-pay will be refunded if your upgrade does not clear.