I hear you! It is so difficult and frustrating to meet these ideals with all the obstacles in the way, the biggest being a lack of SSN, means no bank account, no DL, no state ID, limiting access to so many things that would be helpful. We also delayed filing as long as possible until we had what felt like enough evidence to submit. Kinda regret that now with the current immigration environment, but didn't feel we had much other choice at the time. With how expensive it is, we wanted to feel confident that our application was sufficient first time. Knowing what I know now I've been through the process, and in the current climate, I'd say submit everything you've got and then kept uploading more stuff as and when you get it to add to your case. I thought the initial filing was a one-chance shot, it's not, they let you add more.
Like your wife, I couldn't be added to the car insurance because foreign licence, no SSN so no joint bank account. Our child and I were able to be added to work healthcare, but they kept kicking us off every month due to lack of SSN and we'd have to be manually readded. Nevermind, I got a copy of the insurance card while we were named as beneficiaries and submitted that. My husband owns the house, no mortgage, I'm not on the deed or the utility bills. I practically don't exist.
Here's what we did submit at time of filing:
The health insurance card.
Documents re my husband's change of name to my surname.
Family phone bill showing all our names at different time points. (Your mom paying for your wife's phone line is probably a plus.)
Joint memberships for CostCo and BJs.
Community events we did together with our names published in programs.
Joint adoption of pet cat.
Travel receipts along with itineraries of the trips and who paid for what.
Receipts for payments my husband made for our dental care.
Christmas cards naming us all from family members.
Wedding communications with our venue and pastor.
Relationship photos across time, captioned.
Chatlogs across time.
School transcripts for our child, with husband as emergency contact.
Honestly, it felt like throwing spaghetti at the wall, but our petition was approved off this. When we got to the I-485 interviews, we were emailed ahead to ask us to upload any additional relationship evidence we wanted to add. Since our petition was already approved, we couldn't actually upload anything else to that and it wasn't specifically requested for our I-485s. We've been married longer than two years, so I'm not sure how much more evidence they actually would need. We weren't asked for anything else at interview, a couple of questions about our wedding and that was that. Nonetheless, I was terrified going for that interview because it was right at the time they started arresting people at interviews. We had an action plan in place just in case, thankfully all went very smoothly. We had an RFE at interview so not approved yet. Submitted the RFE and waiting now. Good luck to you both!