If you are in danger of paying your mortgage late, send your payment via overnight mail. The cost of doing so is probably much less than your late payment. For example, a 5% late penalty on a $1,000 payment is $50. Sending the payment via Federal Express will cost you less than $15.
Perennial mints, including spearmint, applemint, and peppermint, are very vigorous and can become invasive. Rather than planting them directly in the garden, grow the plants in containers, then sink the containers into the garden. This will contain the roots and limit spreading.