I'm a US citizen married to a Canadian citizen before our PR app was sent in we had trouble crossing the border. I was never denied but asked tons of questions, the last crossing before I applied was downright brutal. We live in a border town and in November I was given a 1 year VR, I was told I can now live in Canada but cannot work or study. We now cross without any issues. We have even crossed with my husbands kids without any questions. I usually cross about once a week for a few hours to see friends or grocery shop. I never get asked more than what I'm bringing back into Canada now.
When I was given the VR I was told if my app isn't finished in 1 year to come back and they will extend it for me.
I needed to show my marriage license, and our SA approval (as we had it already at the time) when given the VR. I always cross with all my paperwork, receipts and marriage license. It's better to have everything just in case they ask.
Apparently reading other stories on VR's I've come to conclude there is no rhyme and reason on how they work. I do know from this forum others that have a 1 year VR like me that use the same crossing with the same luck I have. I've come to the conclusion that not all border crossings do things the same.
Just bring everything with you that you can to prove you've applied, there is always the risk of being denied entry and if you're going to go across and back you just have to be ok with the what ifs I've learned.