Really a specific use for your booster because unhooking and using jumper cables to the trailer's battery from the truck is going to trump it every time.
That said, some suggestions: use bigger heatsinks or a larger device that will handle more current, using a thermistor in line with the power source will set a current limit to the device.
This is maybe a little hypercritical but a heads-up since I was there once, too: There are all kind of chassis' available and making standoffs are very easy. When i see plastic tubs and wood used for electronics, it always makes me think, "Did the builder have so little respect for his work that he couldn't make a good case for it?". This isn't just about small experimental devices but for devices built to a purpose for fair amounts of money that I see. A good aluminum chassis and PTFE for standoffs is where I usually get to with small boards and devices. An aluminum case will act as a passive heatsink, too.
