No, that’s good. A wooden structure might also be worthwhile, something with a roof and another gutter? Like a lean to. IBCs aren’t made to be permanent, the wall thickness is a fraction of a plastic water tank and can be punctured easily (the cage is why it can be thin). Can you get 200L blue barrels? Daisy chaining them, even a 2x stack is possible, and they are similar to plastic water tanks. Same HDPE, thick walled, UV stabilised, sun not an issue.
Tanks are an investment here. They’re not cheap(ish) but it’s part of the house, a necessary expense even bordering on survival in a way.