i am definitely going to have a go this w/e

That video was my starting point. I initially had my gadget at one end of the box but with all the weight of the box and contents it was tricky to use that way. I tried it in different spots til I found balancing in the centre worked best for me.
I have always used three nylon straps around the box to hold it closed so I thought to loosen the centre one, slip the gadget into place, and subsequently re-tighten the strap so everything was tight. It worked.

i quite liked this solution https://youtu.be/IG8Dq-WuUYE

but it does not appear to be on sale anywhere and might be a bit more tricky to manufacture at home

that's so helpful and such an ingenious solution - thanks v much

And sorry, no other photos.

Yes, runs and front to back and is centred. Yes, the strap runs around the middle. The strap keeps it from falling off if I have to life the box. The bolts bore in to the bottom of the box which prevents the device from slipping around. Once installed, the box kind of balances on the wheels and i just guide it along. Nice for metro concourses, along smoothish sidewalks/roads. In the airport I just use their trolleys.

this is a great idea although i am trying to picture the orientation of the skateboard in relation to the box - does it run front to back? and the strap runs round the middle? do you have any pictures?

Great photos - we were just there and I recognize most of the spots. Your photo of the semana santa statues and the police station are top notch.

Haha. Same here - the 1980s Brent had smaller feet!

Lucky you! The shoes I bought in 2018 are now desperately in need of replacement. Their predecessors were purchased after our first bike trip with the kids in 2006, when I realized my feet were bigger than they used to be.

I'll certainly be placing the maps within the next few days.

Maps are so helpful. Even if it's an area I will never bicycle, I still like to orient myself to where the rider is. I especially appreciate maps if I plan to tour the area myself, it takes the guesswork out of planning. Also appreciated are the names of lodging and restaurants - both good and bad.

Thank you so much! I will be adding maps from my GPS shortly in case you're interested. I haven't had a moment to upload them yet.

I've enjoyed following along with you. Thanks for the informative journal.

Yes. The nylon straps have nylon clips that allow me to easily loosen the centre strap so I can slip the skateboard in /out and then retighten the straps. The gadget is really light so I just buried it at the bottom of a pannier until the end of the tour.