You can travel on B1/B2. We did it several times. If you're worried, go through a preclearance airport if possible and bring evidence of ties to your home country (job, housing, proof of funds, etc.)
You can contact the airline and get proof of travel. I was able to get PDFs from several airlines showing we traveled together with seat numbers, origin/destination, dates of travel, etc.
But, in the I-751, there's also a section for the spouse, under "Spouse or Individual's Statement" to say they have requested the services of an attorney. Page 7, Part 8, Item 2.