Motorhome Battery discharge

thecat

Looking for some guidance please!

I have an Ace Milano and the the alarm/immobilisor gradually discharges the vehicle battery. I have previously used the switch on the control panel to charge up the battery from the mains hook up. I was advised not to do this because the battery was getting
hot and reducing its shelf life. I don't want to disconnect the battery (as suggested) and try to drive it once a week to top it up. However this is not possible all of the time.

Could I connect an optimiser to the battery and plug it into the van socket, link the hook up and safely maintain a trickle charge? I have my motorcycle on a constant trickle charge and have never lost any starting performance.