Intelligent maintainer combined with remote starter is the best of the best.
Well perhaps adding 'pre warming the cab' would top that.
A timer to switch on the heat helps as does also a wireless remote control, (which I prefer).
Then like my friend, he simply leaves his heat on all winter. (his landlord gets the hydro bill)
Caution:
Beware that GFI's tend to disconnect whenever they smell snow. (ask me how I know)
There exist both fast and slow glow plugs, just to explain his long count.
Your worst nightmare ----is needing to replace you block heater at -20 deg.
A 1 am trickle is made to keep a full battery charged, but will not charge up a drained battery. The 6 am is made to recharge a battery.
Your battery is probably on the way out for whatever reason. Old, alternator not recharging properly etc..