Please Help With Paint Questions

That is good to know. This paint system is all 2k, every step of the way, and there is a clearly marked "epoxy thinner" sold to be used with the 2k high build primer.

 

I've had quite a bit of experience with Awlgrip. 545 primer is really considered a finish primer and is designed to be used prior to the finish coat. If you are looking for more build Awlgrip sells "Hi-build & Ultra build" primers, Ultra build gives the most build per coat, hi build give slightly less. In either case these primer should be over coated with 545 before applying the topcoat. Topcoats will achieve a much better appearance when applied over a finish primer rather than a hi build primer.

The solvent in all of the above mentioned primers are safe over 100 solids epoxies such as West Epoxy as well as gelcoat. If you want to test for comparability there is a simple test you can perform.

I noticed a comment about Awlcraft 2000 and Imron being the same product, while there are some similarities the products aren't the same. The hardness, repairability, mix ratios, among other things vary in the products

 

OceanNavigator2, some of the larger concerns regarding use of industrial products in the marine environment are flexural properties, intracoat adhesion, and temperature variation/extremes. Most industrial epoxies are NOT made to flex, and your boat most certainly flexes. How will your industrial product perform under these flexural strains?

As this thicker layer in your cake (coatings systems can be thought of as a layer cake, to some extent) flexes, how will it's bond to the other layers perform both underneath and above throughout it's service life? Remember this layer will be thicker than it's surrounding layers, as it is intended to build, yet the film thickness will also vary during application. Will this layer be able to flex evenly and retain it's physical and chemical bonds to it's surrounding layers? Most building epoxies require a prep/intermediate layer to be applied before the build layer.
Temperature will also play a large role in the performance of your coatings system. Dark paints can achieve +200 degrees F in direct sun. Your boat may be subject to temperatures below 0 degrees F in the winter. On spring days in the Northeast US, temperature swings in coating systems can be over 100 degrees between shade and sunlit areas. Boats at docks can see repetitive shade lines. Will your industrial build layer be able to perform under these extremes and retain it's bonds?
The marine performance coatings market has demands that exceed most other application environments, and the successful primer products are the ones that meet these demands. Many have tried........-there is a reason that most marine painters prefer to use the same build products, but vary the top layers to suit the customer. There is very little that is more expensive or frustrating to replace than a bad build layer buried in a paint job.
Industrial products also do very little to hide print-through-which should be a very valid concern in an e-glass application such as yours.
Industrial aliphatic urethanes come down to color and gloss expectations in the marine environment. Most can not withstand the ultra-high UV exposure, or the inexpensive tints do not last requiring a high volume of buffing, which is problematic with these coatings.