I should get my head into the current scheme of things. Spurs me on all the more to continue on the path that I am on.
No, no, you misunderstand...I think most all of us are just jealous of the fact you have a "cool" wheel. In fact I have been looking for a set for myself..!
Mike...Ya got me! Google is not my friend when I search "regail".
Ok...so I didn't look up the spealing...
regale is the correct spelling.
As far as your plate...I understand completely how you want to use it...and I still wouldn't use it that way..! Especially a .500" thk. plate... That'll weigh almost as much as the wheel...!
If you want to help strengthen the center of that wheel, or any wheel with three patterns (material strength wise...is an excellent reason NOT to run them), is to make the plate part of the wheel...not just clamp it onto the center of the wheel.
My thought is to actually use the outer 5-1/2" B.C. AND the 4-1/2" B.C. to drive and support the wheel.
On one hand, the 1/2" or so between the 4-1/2" and 5" patterns give very little radial strength and even less bending strength. And as I hinted at before, when going around corners, wheels really do..."get bent" by the weight of the car and the traction of the tires. As you can imagin, the fronts normally take most of that load..!
Anyway, with an outer "plate", this will help the bending moment a little, but wont help the inline loads at all.
Having the wheel center squeezed between the drum/hub and the plate gives little to no additional strength, inline of the lug studs. The only thing you'll get is a "friction" strength....and this wouldn't be good for a go-kart..!
Now if you were to add...tight fitting drive pins, so to speak (in the 5-1/2" pattern)...in the outer lug holes...this would go a long way in providing additional strength in line with axle rotation and also some additional support for the bending (cornering) loads. Still not perfect, but much better.
As far as redrilling the hubs/axles, I'm not positive, but I don't think there's enough material for a larger diameter bolt pattern. Obviously best to measure though. THAT IS the best way of doing this deal.
Hope this helps with my concern...
Mike