That's true..I have tickets. But I didnt have it at that time.
If i crossed border by car, it will an issue.
I have a friend who had multiple visits to the US but he always flew there and back and he showed the tickets to them on his phone at the interview when he was being asked about it. Later I believe he even printed those tickets and went and gave it to them.. I guess he asked them if he could do that before dropping them off..
Anyway.. I hope it works out for you..