I geuss my comments will come too late for you , but this is a nice paddle, Lorraine. As Cam suggests, look at the bcmarinetrails web map for info
https://www.bcmarinetrails.org/bc-map?mapitem=6886
When I was last at Tunstall Bay, there was more parking than at Bowen Bay and no posted restrictions on parking. That doesn’t mean to say necessarily that overnight parking is permitted – most municipalities have blanket by-laws (such as in Vancouver) that don’t allow it beyond 24 or 48 hr but it is complaint-driven, meaning that you have to irritate a local resident enough to get them to phone the by-law control officer to get you ticketed or towed. Some coastal areas seem to have curmudgeon-like vigilantes who delight in doing just that, but most don’t, thankfully!
I would not be concerned about currents. You might get 0.5 to 1 kn. I’d be far more concerned about wind – this area is a classic wind funnel and gap winds will often exceed nearby winds. Sailors love Barfleur and Collingwood Channels!