The leisure batteries and the engine battery are two different things. The engine batt needs a high current to start the engine. And will be loaded by the alternator. My preference is to keep this out from the leisure.
i advise if you are technical to read out component location from engine cooling,,Emission control, intake air distribution and filtering, Electronic engine controls.fuel charging and controls- turbo charger. And how it works.
A awning on your van or motorhome is the most critical item you can have. it can blows over the top roof and damage your roof windows sun panels Etc. anyway have it electric whit a wind sensor as i have at home. Nobody now how they really are attached by bolts and back plates. Just hear the sound when winding up.