You can try few powered devices which should act as repeaters to extend the z-wave range. Using z-wave bulbs definitely will give you a nice mesh. However, z-wave mesh goes maximum 4 hops and personally I found that sometimes and only sometimes, battery powered devices that hook after the last 4th hop might not always report their status (sensative devices in your case)
You can try the un-orthodox solution of adding an external antenna to Homey Homey antenna mod this in combination with powered devices has a good chance to fulfil your needs.
