Any suggestions how I could do it?

My caravan is stored at home but has to be parked with the battery box right up against a wall and I need to use the motor mover in order to get the caravan out. Consequently the battery must be permanently kept in its housing. For a few years I have maintained the charge in the battery by having the inbuilt charger (Sargent EC175) come on for two hours each day. This has maintained the battery voltage at 12.7 / 8 without any apparent problem.

I am considering buying a 4 amp smart charger, essentially for maintenance of car and other batteries but wondered whether using it on the caravan battery would be beneficial. The problem would be how to connect it to the battery. The charger would need to be inside the caravan but, of course, the battery is in a sealed from the habitation area. Is there any other point that I could safely connect the charger to? I had considered seeing if I could connect to the battery side of the motor mover master switch which is inside the bed locker, adjacent to the back of the battery box and in the housing for the existing charger.

Am I creating unnecessary work for myself?