Things don't always work as "supposed to" in computer games
However, one could always try improved invis on the rogue.
Or, the cleric could grab the stuff and then do a sanctuary.
Or, you could cheat by having the party at the exit except for one, grab the stuff, jump the person to the party, and leave.
You could even - dare I say it? - not take the items at all.
Nightowl2