Just spotted the DD 'pathfinder'. Inner / outer available separately but the outer weighs just over 500g and they say is big enough for 2 to sleep side by side. Requires a single pole.

I reckon pitched as the picture, it'd be something of a condensation generator but raise it a few inches and it'll likely be much better. It does have a vent at the apex but a single vent is utterly pointless if air can't flow - also not helped by the fact that once air has reached the apex, it then needs to travel downwards in order to reach the vent opening. However, poor vent design aside, it might well be appealing to some.

Outer appears to be around £110.