First rule of home automation: “the model number matters.“
In this case, it’s the protocol that matters.
Zwave plus devices have significantly longer range than zwave classic devices.
And there is a new generation, zwave plus V2, which will have even longer range yet, although I don’t expect to see devices with that available until 2022.
Anyway, one of the other issues for Z wave devices is that they don’t tend to transmit very well through rain, snow, or high humidity. So that can reduce the effective range, although they will do very well in dry clear air.
Also, I was a little confused by your description of the network layout.
Z wave is limited to four hops per message, which doesn’t count the origin or destination devices. So it’s like a relay race Passing the baton from the first device to a maximum of four “runners“ and then the destination.
In practice in a building with wooden walls and not too much insulation and no interior wire framing you can expect zwave plus to have a good range of about 75 feet for each “hop.“ You may get double that if you’re lucky, but it’s not something you can count on. And again it may be somewhat less on rainy or snowy days if one of the devices is outdoors. But if you have brick or adobe walls or walls with interior lathing or large metal objects (including automobiles) or trees in the way that can all reduce the effective distance.
Even in bad weather conditions you should be able to use zwave plus to cover 300 feet with four hops from the hub to the furthest device. But I’m not clear on what your layout will be.