CMC PT-35 on Old Polarkraft Jon Boat

So i picked up a CMC pt35 for my 16ft jon boat, i have a 1981 35HP evinrude to go with it. I was eyeing up the fit last night and the first thing i notice is that i have a bunch of small bolts that go through my transom to 3 gussets in that brace from the transom to the bottom of the hull. Each gusset has a 4 bolt pattern (2 bolts on each side of where the brace interfaces with the transom). The middle gusset bolts are dead center and the PT35 will cover all 4 bolt heads, the left and right brace look like the edge of the PT35 may go through the edge of the two inside bolt from each gusset. How should i deal with this?

I see two options:
1) use a piece of marine plywood thicker than the bolt heads, put clearance holes in the wood to create a stand off. Bolt the PT35 through the standoff.

2) Drill out clearance holes in the PT35 for the middle gusset and use longer bolts to bolt through the pT35, transom, and gusset. For the Left and right side gusset bolts i would just remove them and silicone the holes up.

Thoughts?

I suppose i could use 1/2 inch thick poly board or something like that vs marine plywood

That sounds like an interesting idea. Maybe make a prototype out of plywood.

I like option 1. Since this is for clearance rather than structure using poly board or any waterproof curtting board material seems like a good idea. I would put the "clearance" holes all the way through the poly board so that there can be some chance of drainage in case water gets trapped.

Thanks guys, I will give it a shot, seems like it will work well.