Ram seals just wear out if they are not exercised often. It’s an easy fix if you can get everything turning. The end cup wrench is a requirement and they come with the sea star rebuild kits. It sounds like you know about these since you mentioned the thread protection cap. I find that if I just spin the wheel when on the trailer between trips my seals last longer. Boats like to be used. I think your props are really close to what I have. I’m hitting 5800 wot and that’s exactly what I wanted. Sweet spot is 3500 rpm. My engines are 2019’s leftovers. These boats are never ending work but it looks like you nailed it. Regarding your trailer, I would say at least 5-6k. It just made a big trip so it’s road worthy. Price depends on what part of the country. That’s would go for a lot in southern California.