Cargo Super Heavy Super Safe

I have been the beneficiary of poor @platypus' misfortune.

My hope is to rebuild this Babboe to:

1. Include a full width and length box for transporting stuff back and forth between an allotment.
   
2. Take detachable and comfortable child-seats and have some sort of waterproof canopy.
   
3. I want to be able to share it with a couple of other families in my neighbourhood so some reasonable adjustability of fitting (will probably be limited to seat height I'm guessing).
   
4. Project will include outdoor security so any ideas are welcome, lest a similar fate befall me as my predecessor.