I will offer one suggestion, if you are comfortable doing so.
Along with day trips, we often take side trips for a night or two out of a main hub. We will leave our large bag(s) with hub hotel bellman (which are locked up) for a few days and take just a carry-on/backpack with essentials for the days we are away. Real easy to do if you are returning to same hotel for a night, but I have also returned to hub hotel to simply pick up the bag before taking a train out of hub city to our next destination. Very easy to do if hotel is close to train station.
Knock on wood, after 64 countries, I have not yet had one issue, damage or a stolen items from the bag. I do lock them, but still. I also do not leave valuables in the checked bag.