Thanks for the link Bob. I think I would be o.k. just coming home and putting something in the back.

The offence is:

It is an offence for a person to be in charge of a motor vehicle on a road or other public place with excess alcohol in his breath or in blood or urine as evidenced by a certificate of analysis or statement.

I think this would help my case:

There is no legal definition for the term "in charge".

Anyway, I don't believe it will ever be an issue.