For me it’s either 600m to a small corner shop or about 1.1km to a larger store.

I do 3km periodically for another store, but I wouldn’t do it in 30c weather. I’m barely willing to exercise in 25c weather.

+1 for Unraid, as it’s what I use, but truenas I believe has array options which support your plans no problem. It’ll do a similar software raid solution which allows you to modify the drive pool later on.