You might be able to add some spacers between the motor plate and the bracket to create some extra clearance there, or shift the plate higher on the bracket.. (though this might cause earlier prop cavitation so watch out for that)
I've seen this problem before, often when the motor is tilted up for sailing.. While disconnecting the fuel line can be a PITA, it may be the most sensible tactic.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)