Your MX record will point to a FQDN (A record) not to the IP itself. Likewise, if you setup an SPF record that is adding your MX record as a good sender for your mail, it is not using your IP either (as your example shows you are adding the MX record to the list of sender).
So the only piece left is maintaining your A record to point to the correct IP, which if it is dynamic means you will be changing it regularly.