You could, but you will lose the watertight seal where the cable enters the connector and have no strain relief due to the diameter of the micro and mid cable being much smaller (7.2/8.4mm vs. 11.3mm for the mini).
I did an extensive (read: complete) refit
of our boats networking after buying
it and tried to save some $$$ where I could and looked at various brands of N2K cables
. Ultimately bit the bullet and went with all Maretron, there was just too much difference in quality and I only wanted to do things once. One suggestion, after installing the new end be sure to test your cable using a multimeter to make sure all the connections are sound. The micro/mid connectors are a PITA to wire and N2K is not tolerant of connections with too much resistance nor other wiring
issues... I learned that the hard way! Maretron has a document somewhere on their website that tells you how to test a cable.
In thinking about this a bit more, you could conceivably build up the diameter of the micro/mid cable using something like rescue
tape or maybe electrical
tape where the cable enters the mini connector. Just a thought... probably not a very good one.