I think this is one of my favorites of your designs. It's so refreshing to see new shapes incorporated into kitbashed Starfleet, and the Leif Ericson integrates well!
She's a lovable old barge, nice action pics there. In canon trek only the Sydney class had the look and feel of a freighter/transport I happen to like that class a lot as well.
The model is 16 1/2" long, so at 1/1000 scale (which is what the PL nacelles are), that makes it 1,375 feet long. Yoikes, that IS big!!
If the real world is anything to go by, cargo and freighter type ships *are* the biggest ones around!