Hi Almot,
The biggest difference is being able to use a single high quality pwm controller. Wire from the panels to the controller can be smaller, too. (example 12 volts @ 200 amps = 2400 watts vs 48 volts @ 50 amps = 2400 watts). The first part of the example would require two Magnum pt-100 controllers @ $800 each. The second would require one Morningstar 60 amp pwm controller @ $240.00. Obviously wire to carry 200 amps is going to be a LOT thicker than that for 50 amps.
The conversion losses may be smaller as getting from 48 volts dc to 120 volts ac, is a lot easier to do.
There are quality dc to dc converters that are inexpensive.
Almot wrote:
With 48V bank only the wire to battery will be thinner (where it's not too important as it's short). The wire from panels to controller won't change, and the dance of parallel/series/Vdrop will be the same.
Controller will be smaller and cheaper, yes.
A DC-DC downconverter will have to be installed after the battery, to handle 12V loads of trailer - costs $80 or so.
