I have travelled on some adventures over several days on a motorbike and a bicycle.
I have taken both a plywood Yamaha GL1 and an OU soprano on the adventures, without a hard case. The OU has been tied on the top of a rack without a bag of any sort. The Yamaha had a rain cover only. I posted the OU home in a parcel bag. So even a plywood uke will survive a lot on an adventure and the eKoa and MFC ukes are tougher than plywood, although like plywood you may need to have a rain cover to keep them dry.
The instruments did get some beausage, mostly because I was able to use them without a lot of unpacking. It is nice to be able to play a piece at a nice place where you stop for 20 minutes or less for a break and a photo.
I have seen an eKoa uke, but don't own one. The videos do not show you how tough they are for fun, the makers want you to use them. I would forget about being limited by the purchase price and focus on getting your money's worth by keeping the instrument in easy reach so you can use it without a lot of effort, especially if you are on a uke orientated adventure. Either the MFC or the Clara instruments would so the job.
For backpack carriage, I have made a simple box or holder or holster out of a material called signboard or Coreflute and duct tape. You put it in the backpack and it keeps the place of the uke when you pull the uke out, so it is very easy to get your uke out and put it back when you are travelling. As it hides inside a backpack, no-one sees it and you do not need to worry about cosmetics. Coreflute also offers some protection from scratches and stuff inside the pack. One of the ukes has a ripstop nylon liner bag for the corflute holster. First you measure the uke and trace around it onto the Coreflute, and you look at your backpack, and work out a top loading design, cut it out with scissors or a craft knife and tape it together. Get enough material to make a prototype, its not expensive. The prototype should be done as a practice which you may not use, once you get the idea it takes about an hour per uke. Also you can laminate two sheets of 3mm Coreflute together with the grain at right angles (I use double sided tape to hold them together) , and you get a very stiff and strong material 6mm wide which weighs a few grams. The ones I have made have the headstock down inside and the body at the top, this may not work on a shorter backpack, but it allows easy top loading.