There's some stuff on Orbitz for an SFO - DUB MR which goes through LHR o/b and FRA i/b. It's around $520 - $600. If you can take off Friday, you can return Sunday (overnight in FRA).

Question: If the termination point is DUB, what's the minimum time nec. to get the return ticket if not leaving the airport? Is it possible to do that airside (like at LHR)? This, of course, assumes that at some point some carry-ons will be allowed.