Riveting dilemma

[rippie]

I am ready to rivet my rear belt line (floor is in and bolted). Everything is in place. But I am hesitant because of the space that is greater than 1/8inch between the skin/hold down plate and the c-channel. The skin is approximated properly on both sides and clecoed in place. My concern is that if I do not get a good approximation at the plate, it will cause weak joining and lead to shearing down the road. I am also using Olympics ( I know, I know it should be bucked).

My current thought is that I should loosen/remove all c-channel bolts to allow it to move and close the gap better. I also have a strip of aluminum from Home Depot that I could place in the space to prevent gapping in case I decide to go that route. But I am leaning towards the first option. I was hoping to get some comments to help me decide which way to proceed.
I haven't seen it mentioned, but it makes me wonder if the plywood shouldn't be notched to accept the hold down plate.

Picture shows gap with alum. strip inside.

[rippie]

Hey. I just wanted to run this up the flagpole this morning as I had no responses last night. Maybe morning coffee will help. Sorry for the self promotion, but I would really like to work on this today. ANY thoughts would be appreciated. Thank you.

[SSSabre]

I prefer to adjust for proper fit as much as possible, and keep the shim necessity/thickness to a minimum. If I was doing the work, I'd loosen the bolts and see if there's enough existing slop in the bolt holes to adjust the channel. This, in combination with a shim if the gap cannot be completely closed, will do the trick.

[Aerowood]

Try to do it without the shim or just shim the minimum amount. I fabricated the hold down plate longer and it spans between the two vertical ribs and rivets too the ribs skin and "C" channel. It took a soom pretty long rivets.