Good evening, Cdnpr2017!
I am a US citizen and went through the process of becoming a Canadian PR through Outland. I crossed daily for two years and was given my fair share of issues, but I have to say, I was given a much easier time crossing when I had my application going and everything paid for. I crossed with my common-law partner one day from Michigan to Ontario and asked for a visitors record, I have to say it was nerve wracking, but ask for a visitors record! Have a copy of everything (your application and receipt of payment) and mention that you want to stay for the given time and you have an application in process with everything paid for. As the officer mentioned to me when I obtained my VR, this allows you to stay in Canada while your application is in process but you are still allowed to cross as need be.
I am unsure of your exact situation, and please keep in mind that every situation is different, but for me this worked and others should be aware that it's possible.
I hope this helps!