There were nuts you bet, I took a slightly different approach and broke the plastics sliders apart with a special breaking tool (a hammer and a screwdriver
) and then cut the bolts and retrieved the bottom half out of the bulge after.
You are correct that the only access is from the engine bay behind the trim pump. It is not a nice fit but building the clamp down using a piece of flat aluminum and gluing washers and nuts to it then leaving it to set overnight you can just reach and it holds together while you get the bolts started from the top side (2 man job, skinny guy inside the boat) then a long handled ratchet and socket (I used my torque wrench as it had a long handle) you tighten it all down one at a time.
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