see window unit AC ventilation evap kooler heater installation kits in Remodeling here accentuated for van trailer conversions Toilets, AC, fabric showers n' furnishings, shade
The low cost of entry market can be optimized. If you commit to giant fixed panels with long cable runs. But now you can't park in the shade and move your panels in the sun.
A buck boost is a plain PWM in buck mode, and efficiency should be higher with a bigger converter to limit your I squared R losses ( i believe parasite losses go up and it is harder to cut off the parasite losses by shutting down inverters and relays to controllers etc)
In any case i will have optimum small portable/modular configurations soon. I have a small buck boost type with the lowest sold parasite draw, but it has voltage range an current logic that makes it unusable in some situations. Field tests against plain pwm often show no yield advantage. The there is cost/ replacement availability.
There's no reason a decent buck/boost converter should not be excruciatingly reliable
Coincidental that human bike power is small, dashboard starter battery maintenance is small, toilet is only 18 watts plys some for out house lighting.
I think you're optimizing around the wrong thing but that's your call
Each brand of small controller also has peculiar idiosyncrasies and divergent philosophys. I dont intend to build components, it is more choices in assembly.
When your victron van breaks in utah, you are screwed. If part of a panel is in the shade your whole system goes way down. If you break it down to smaller systems you van get a quick inverter and cobtoller at walmart/harbor frieght.
Smaller non integrated systems, parasite losses, cost of entry/building blocks, portability, wieght of panels, installation cost issues.
You already looked into the van conversion hardware?
Now car covers need a window.
Testing charge contollers for bike, toilet, dashboard-lipo starter battery. Chaos, No competent supplier exists. Next panel will be all black with ventilated support behind.