Actually, that isn't the problem. Bluetooth does NOT require "line of sight".
If you have a smartphone, laptop, tablet, or similar device, it is probably equipped with both Bluetooth and Wi-Fi wireless capabilities.
www.britannica.com
It is also not true, except when a manufacturer specifically designs their implementation that way, such as for headphones etc., that it is designed only for short range communication.
Bluetooth CAN work at distances up to a half mile, if it is implemented in that way.
Blog Perhaps a victim of its own success, the global proliferation of Bluetooth® technology in headsets, phones, watches, and cars has sparked multiple myths about what the technology can and can not…
www.bluetooth.com
The real problem is that Bluetooth does not work well through walls or other obstructions. It doesn't require line of sight, but it pretty well does require that it not be surrounded by an enclosure like in a room with any doors closed and while it can bounce off objects much as any radio signal can, it does a hell of a lot better if there are NOT any obstructions and there IS a line of sight. But that pretty much goes for any over air signal. Even so, I'd agree with you that WiFi is probably the much better option here and if possible, even simply networking them together using ethernet cable and switches or routers would be far superior.