Chris,
Attached are an older photo using the cart with backpack on the Missouri Katy Trail plus newer photos showing the current configuration using a piece of luggage.
My use is a combination of city sidewalks, streets, shoulder less two lane roads and rail trail conversion. Roughly 50 miles metro area walking in St Louis and Kansas City. 260 miles on the Katy Trail and Rock Island Spur. Katy and Rock Island Spur trails are crushed limestone surfaces.
I prefer the luggage for my purpose as once the luggage is more firmly strapped onto the carriage and hiking poles, I only need unhook the vertical center strap to access the luggage. Lucky find in a dumpster.
I used a plastic sheet and construction sealing tape to fashion a rain cover. I pack everything in gallon bags so the cover is secondary protection.
I have done two treks now between St Louis and Kansas City for my Cross Missouri CROP Hunger Walk fundraiser. Average daily distance is around 24 miles. Rolling the load makes this very doable for my being 69. With food and water added in, the cart is at 30# total weight. I could not carry and walk that distance.
I also have appreciated your good communication with answering questions. I promote your Trekkers Friend to many that I meet on the trail. I get many inquiries as folks think it is something I cobbled together.
Thank you,
Don