Going Fiat-Free?

How would one go about living completely or nearly Fiat Free? Keep your main stack in Cold Storage and then spend as needed with something like a Coinbase debit card for monthly expenses? Assuming your stack is big enough to give you a big enough buffer for monthly expenses (even if the Fiat price of BTC goes down significantly). Does it make sense to do this if you actually believe BTC will go up significantly in the long run? Maybe just keep one month of expenses in a fiat checking account, and all other excess cash into BTC cold storage? What should the value of your BTC stack be VS your monthly expenses? (For example if all your monthly expenses are 5k, should your sat stack be worth at least 30k in fiat in order to cover 6 months of expenses?