Our cat 4 coded Humber has a similar arranegment, the main tank is in the console under the jockey seat, the electrics are all contained above in a locker accessed from the front of the console.
One thing to consider is that you will need a gas alarm if the space the tank is in is sealed. Alternatively, you can add sufficient ventilation close to the deck (to 'drain' the fuel vapour) but you will then need some way of sealing the vents for wet/rough conditions to stop it filling with water. Our surveyor suggested a 40mm hole at the lowest point and carry a rubber bung!
__________________
|