So what am I gonna do with this?

Just gonna build the sound system myself. I know a bit about speaker design and have a bit of experience with building trash-trawled pa systems.
Got a couple of 18" bass bins in newcastle, but i think they're just too big!
I think it's gonna be best built into a separate trailer which attaches to a bike. Just thinking about what the best way to do it is.
Design ideas are very welcome!

take some close ups if the back axle and i can whip up some designs. this is too sweet not to be a trike. should be easy enough, just use an old shitty girls bike frame