Craig,
Sounds like you have a good amount of data for a very nice mosaic.
Any wide field image with such a low resolution lens, focus will be critical. For both a good image and for the image solving. When I find focus with my camera lens for the night I tape the focus ring to the lens body. I use manual lenses. This prevent any chance of a mishap during the nights session. I also use a dew heater and large sun shade. I hate surprises.
Since my image captures are so different in quality it's hard to give you a good detailed workflow. Each image required very different parameters. The best suggestion I can give you is the normal start of DynamicCrop,ABE or DBE. Do a color calibration how ever you want. Then its noise reduction and stretching. I like the new MLT and then MaskStretch. From there it is really image dependent with wide images. That is if you have variable sky conditions. I used ExponentialTransformation and the Background Enhance script in many of my images.
If you can build your mosaic from images of similar qualities then start with crop/ABE-DBE and ColorCal. Then build your mosaic with the linear images. This will allow GradientMergeMosaic to do all your blending. At this point you can then process the whole mosaic for a better quality image. I could not do this so I manually used Statistics and HST to get as even of a background appearance as possible across all panels.
In ImageSolver with processed, wide field, non-linear images I start with a magnitude limit of 8 and if needed raise it. I use Bright Stars and Polygons. Make sure you have your pixel size and focal distance set. I always check that they are correct. If you resampled your image then you need to change one of these settings to follow the resampling. You might also need to change the Star sensitivity setting. Once you have your image solved check it with the AnnotateImage script and the Constellation Lines. If the registration is off try ImageSolving again with Triangles. I've had a few very wide images where this makes a difference.
I missed an important bit of information When solving wide images. Try to pick an object close to the center of your field of view for the object search. Or if you know the coordinates of the center of your image use that.
With patience I haven't had many images that ImageSolver can't handle as long as the resolution isn't too low. The other option is to use CatalogStarGenerator and ManualImageSolver.
I hope this helps.
Mike