About two weeks ago I set up an outdoor gateway using RAK's 2245 starter kit.
I took the advantage of having available an IP66 rated fiberglass reinforced polyester enclosure accomodating other equipment and found a place for the little boards sandwich inside. The antenna is RAK's 5.8 dBi omni available here and I can say that I'm more than happy regarding the overall performance of the system, considering it's low price; including custom tax, shipping, wiring stuff and power supply was about 300 euros).
Having the antenna installed on the roof of a 5 floor building, having similar buildings around, I got a maximum range of about 12 km in a hilly, suburban area. TTN mapping is available here.
I will possibly need to install a fan with a thermostat; for now, Pi's processor temperature did not get above 50 deg C, for an average ambiental temperature of 25.