Dawn - first let me send a great big hug.
There are lots of things you can cook. You can roast various vegetables (broccoli, cauliflower, beets, turnips, mushrooms, shallots, grape tomatoes, etc.). All of these tossed with some pasta and drizzled with more EVOO, kosher salt, pepper, make a great meal.
You really need to turn to his doctor for some help. Be assertive about needing help with his diet. There are proteins in lots of things we don't normally think of.
Also, I understand your trepidation in a transplant. You also need to sit down with his doctor and discuss that. Tell him/her your fears. Let him/her tell you what the quality of his life would be without a transplant as opposed to with a transplant. Take a friend with you for an extra pair of ears. Have him/her write things down that the doctor says. I know from experience that when there are medical issues it's all hard to take in and remember.
I wish I could help more. Even though I have kidney issues I just don't know enough to offer any definitive advice.