Gazza

Mate, I did exactly this in my van before going permanent. Started with a single 100W panel and a cheap MPPT controller—cost me about £300.

Right, I've had this dance with my van setup. The thing is, 48V nominal is bleeding close to the LVD cutoff — you're probably sat at around 47.5V under load before it trips, yeah? Worth checking:...

Ran a similar T5 setup for eighteen months before upgrading. That 400W will get you through spring/summer no bother, but come November you'll be rationing the kettle.

Right, I'll add to this because I've been there myself. Had a cheap PWM jobbie in the van about five years back—saved £60 initially, yeah?

Ran a single Drift 5.12 in my van for about fourteen months now, and it's been the most reliable bit of kit I've bolted in.