I don't think your technique would work; I'm sure they would ask you why you would want to do that because you have Elite status on one.
That said, you could always try and send in your boarding passes for credit.
HOWEVER, in theory you should be able to pre-select a preferred seat, but I'm curious as to whether or not AF will give bulkhead or really popular seats to non-AF elites.
Anyone have any experience with this?