Glad to see the OP negotiated the border both ways without too many problems.
We cross into the US from Canada occasionally with the Airstream and we've had no issues so far (other than the three hours wait just to get to the booth last time!).
On the issue of food, we simply play it safe and take no food whatsoever when we head south. This may sound like overkill but there are a number of circumstances that make it a practical option.
Firstly, there are plenty of good places to buy food in the US. It's marginally cheaper, too, so we always schedule a grocery stop once we're over the border. If we're going to Upstate New York then we HAVE to stop at a Wegman's.
Secondly,we live close(ish) to the border so it's always at the start of our journey; we don't want avoidable complications at the start of a trip.
Thirdly, I'm traveling on a UK passport, which can sometimes require a stop in the office to get the paperwork sorted; painful enough but with the added complication of a "Fruit Violation" it could get difficult.
So, no food at all works for us.
We crossed at Windsor/Detroit early one Sunday morning and the border guard clearly didn't believe me when I said we no food at all, so he headed into the trailer and did a search. He looked sort of crestfallen when he came out and I so wanted to say "I told you so", but thought that wouldn't be a wise move