It wouldn't meet the legal test - it would be no different to taking money from a till and leaving an IOU note in it's place.In the OP's case they are suggesting their own meter, presumably MID-compliant, until the official meter is installed so it might fail the test of dishonesty for any prosecution as they would be measuring and intending to pay for the usage.
I suspect it would still cause so much legal headache it is absolutely not worth doing!