I am wanting to build a combined bicycle cargo trailer/garden cart. I want the garden function of the garden carts shown below. I do garden/landscaping work all over my city and I travel by bicycle mainly. Having one of these would allow me to haul 200+ lb loads around my clients' properties and it would allow me to bring more functional tools to the job site. Having a cart like this for my work would be terribly useful.
The wheels for the above garden carts are phenomenally strong but they aren't made for going faster than 5 mph. I need something that can go faster than 15 mph since I would be bicycling to their houses. So, I will be using bicycle wheels for this garden cart since they can operate at the speeds that I want. As such I will be using these wheels below since they use 11 gauge spokes and can probably take a beating.
However, this presents the issue that these wheels don't fit into the plans for the garden cart. My solution is to use the chassis from the Malawi Hand Cart plans and then place the framework of the garden cart on top. Here is the Malawi Hand Cart plans below.
For the hitch I was thinking about purchasing the pricey Bikes at Work hitch. Any suggestions on something else that would work better and/or cheaper?
So, what do you all think? Too heavy? Am I over building or not building strong enough? Any constructive criticism?