Here is another idea for an explorer/scout idea. It has a single engine over a standard constitution class saucer. The neck between the primary and secondary hull is used as a larger pylon. The rear section of the primary hull with the shuttle bay is turned upside down and mounted under the saucer.
Probably the biggest change so far to the overall look. I shortened the height of bridge decks, removed the notch out of the front of the saucer. I made the secondary hull portion smaller over all. It is both narrower in diameter and shorter. It will have a smaller diameter defector dish so it won't protrude into the saucer. The warp engines have been shortened and brought in closer to the hull.
Here is my second cut at the light cruiser design. I really wanted two impulse engines and the merged Primary and Secondary hulls. I got rid of the "Miranda" style rear hull and went with a cropped rear hull with two impulse engine outlets. The warp engines stayed in the same spot. I really think this is a much better design.
Here is an idea I had today for a kitbash of Polar Lights Enterprise. I thought I would try and make a "Light Cruise" with the Primary and Secondary hulls merged and the warp engines below the saucer. To fit the defector dish in I decided to remove a chunk of the saucer. I may sling a pod for the torpedoes under the hull. Or possibly on either side of the rear hull above the saucer.