To have a t4 is good, if you have a sin number ( even if expired) you can file your taxes there, go to an accountant to give you more advice, I have an accountant which works with my legal advisor.
There's a lot of cash jobs, also you can create a company, for example " Bradae troubleshooting", but you cannot file more than 30,000 if your sin is expired.
Many would say you should not work cash, however their main focus (government) is that you can take care about yourself (or your family) and don't live from social assistance. Any proof will work out.
All the best