Got them done now
Facial tanning unit a few inches away from the paper actually cut the time down to 2 minutes exposure per image :o so I got this done in a little over an hour yesterday. They're not all perfect but I was doing exposure by timing, not by inspection. The paper seems to react different to the tanning lamp than to the sun anyway so the whole thing looks like it goes blue, no yellow/green bits in the highlights, then again, no "negative" lighting in the shadow areas either. Can be a little bit odd but it's better than no sun and no printing.