Actually, your 50 feet separation has a simple solution – the “Power Line LAN”. Your observatory warm room gets its power from the house. Plug in a power line receiver in any outlet in the warm room, then use a standard Ethernet cable from it to your laptop that controls the scope. In the house, plug in a similar unit(s), into the AC outlet next to the modem/router, (even a third one in any room in the house for your home computer) – or let it join the house link using Wifi to the router or its nearby power line transmitter.
As long as the observatory warm room, gets its AC supplied the “same side” of the house fuse panel, you can have all the PC’s communicate over the home’s AC power lines. The 220 volts that come to your house fuse panel, has two hot power lines ( a red one and a black one), which are split between left side of the fuse box and right side of the fuse box. The router in the house and its nearby AC outlet for the power line transmitter, must share that SAME side with the observatory outlets, It is probably the simplest and least expensive solution for a home observatory LAN arrangement.
I suggest a visit to a PC store, like Best Buy, to discuss these “AC power line modems”. Nice thing is that they are not affected by signal drop outs due to bad weather or nearby microwave ovens, garage door openers, baby room monitors, or cordless phones, etc. However, their signal is not that fast. I suppose if someone started up some heavy machinery, like a lathe in the basement, that might scramble the power line modem signalling, but I haven’t heard of it.