Our club is quite small with a puddle to sail on and shifty winds, Enterpise and Comets go well along with the Lasers, anything with a spinny strugles as there are hardly ever any reaches and the twisting winds make runs well scary. A two sail run often being quicker than the recovery of a capsized boat.
Spinny boats have an allowance made to reflect this and the Ent's are penalised as they go so well.
But what do you do with the sailor who turns up to sail their double hander but can not get a crew? 
We do not want to say they can not sail but most (not all)of the time a single sailor in an Ent or Firefly gets a massive weight advantage and usually clears off into the distance.
I am talking general pursuit and handicap racing here (not personel handicap)

Any suggestions on a sensible way of addressing this would be appreciated, what do other clubs do?

Thanks.

This has been discussed a few times before. Have a read...

We put -40 on the handicap, sailing on a similar puddle - you're lucky, at least you get a can't use a spinnaker allowance. We're not and the RO sees us coming and gives laser reaching zig-zag courses with such short legs there's no time to set a kite.