If you can't sort out H.E.R.'s battery go for a motobatt.
Motobatts are glass plate gel technology, do not discharge as quickly as lead plate acid batteries and offer much increased engine cranking to start.
I've changed to mb's with both my stelvio and 1100c sport, the sport is a single battery replacement for the two battery original equipment and lays on its side.
These are really excellent products, have a look on fleabay for the best price.