if the route is flat, bikes at work trailers Bike Trailers | Bikes At Work are modular and capable of hauling a lot .
2 meters/ 6 feet long , and stacked as high as you dare..

the braking a heavy load down hills with just the bike's brakes is an issue to consider..

putting the debris in a tarp and rolling/folding that into a package would make dumping it like shaking out a blanket.


Building a set of trailer brakes particularly with single sided wheels, does complicate things ,
but you can look to tadpole recumbent trikes for how that is accomplished with their front wheels .

[I just mulch with a weed-whacker and leave the stuff where it's cut.]