I went up to the Canadian side of LOTW a couple weeks ago via Baudette/Rainy River. I realized I forgot my passport as we came into Baudette. I stopped in the US customs office and told them what happend and that I have a passport sitting on my kitchen counter. He said no worries, and that I would need to fill out a short sheet when we came through. He said they get about 10-12 of these a day.
When we went over the bridge into Canada, the agent asked for my passport, I told him what happened and gave him my driver’s license. No problems.
When I cam back over the bridge into the US, I again told the agent what happened and that I stopped into their customs office on the way up. I showed him my driver’s license and, after the normal questions, he waved me through (without a stop inside).
Would I go up all the time w/out a passport – no way, but I wouldn’t fret a 1x mishap like I had.