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#11
That changes everything. Heat is one thing but can be managed. Fumes are what concern me. Over time, petroleum based fumes can eat into some materials. Also, engine rooms don't always stay nice and dry. Neither HDMI nor USB cables are made for "all weather" or hostile environments. If an ocean (salty) environment, that adds yet another hostile element in the mix.About 5 feet of this cable bundle must pass in front of an engine, (20 inchs away) in the engine room space, and it can get hot in there in the summer.
So I think you should visit a marine parts store and talk to them about some marine grade sheathing or perhaps sealed conduit, PVC piping, or the like you can run the cables through with sealed terminations/ends.