The screen shots were great, thanks. The tabernacles I've seen have without exception had the hinge pin on one end or the other of the base. The mast has a flat base bolted to it with the matching hinge on one end. When the mast is raised it sits squarely on the base, the hinge only keeps it form skidding around, the heavy weight is borne on the bottom plate and transferred down through the compression post.
A single centered pin will carry the full weight of mast, stays, and wind. An enormous load. Not saying it won't work, but it simply cannot be even remotely as strong, and I see no point in doing it that way.
Just curious, how did you figure that your weight will be adequate? I'd think you would need to know the actual weight of the mast, plus the distribution of that weight (spreaders, lights, mast head, etc.), and then figure the effect of leverage by measuring from hinge to support at the bow.
Maybe I'm overly cautious, but when dealing with heavy stuff it pays to be cautious. I've raised buildings and large beams and etc., I've seen that things can go wrong and careful thought prevents problems, damage, and injury.
When I purchased my 24 ft. Seafarer it was on stands. I drove to the boat with a plan, lumber I'd sawed out from pine trees or had laying about, jacks and levers etc. plus the almighty chainsaw. I too had people watching as I proceeded to cut the timbers and shape by eye (and cardboard template) and finally moved the 4000 lb. boat onto my equipment trailer, entirely by myself a long ways from home. They were calling me McGyver (spelling? I've heard it a lot but don't watch TV) and were amazed. I had no problems or scary moments, it went smoothly because I visualized it in my mind and planned for every problem I could "see". I didn't want to waste money paying someone else to move it, and like independance.
I'm merely trying to offer insights, what you choose is fine with me, no pressure. And I hope all goes well.
Edit: Perhaps your hinge pin can move in a slot and allow the mast base to settle onto the bottom plate? I'd look into buying a commercial tabernacle and bolting it on. Proven performance on a huge number of boats. Phone call just when I hit submit kept me from looking over my post right away.