We filed my wife's I-751 petition last month, and thanks to this forum, we started collecting documentation from the moment she arrived in the U.S., knowing these documents would be needed at some point.
For our submission, we included front and back copies of her Green Card, driver’s licenses showing the same address, and quarterly joint bank account statements. Since I couldn't add her to the mortgage, I immediately added her name to the utility bills upon her arrival. We also submitted credit card statements and a car insurance policy listing both of us (If you have it add this as well). Additionally, we included eight photos (four per page) documenting our travels together. Plus other proofs.
One thing to keep in mind: don’t overthink or overcomplicate the process—you can only submit what you genuinely have. USCIS simply seeks sufficient evidence to confirm your marriage is bona fide. Focus on providing the strongest documentation available, and remember that quality matters more than quantity.
Wishing you the best of luck with your petition!