Thank you all so much for your help. Heres how things are going at this stage:
2 days ago: Madly dash round carport adjusting height of bucket dangling over gas barbeque(!!). Frantically poke thermometers into sand, digithermometer in glad bags of water. Poke finger into sand as don't believe thermometer. Climb on car roof to readjust bucket for 476th time. Glare at DH who is watching with puzzled look on face.
1 day, 22 hours ago: wake suddenly with new thought.... humidity???
1 day, 20 hours ago: resolve to bug BYC members about humidity, go to sleep.
1 day ago: Wake, feed children and back to playing with bucket, only 2 days till D Day. DH watching with puzzled look again.
4 hours ago: play with bucket a little more, finally accept its "close enough" Re-enter house with somewhat satisfied, somewhat defeated look on face. Sink into chair with over-dramatic sigh. DH asks what sigh is in aid of. He gets the long version of the story. Funny look apears on face. This is how conversation goes.
DH "Oh so thats what the bucket was for"
Me "yep, **** power"
DH "why don't you just use the generator"
Me (in squeky yelpy voice) "
what generator"
DH "the generator you insist on taking camping every summer"
Me <laughs til cries>
Oh dear