Halo+ alarm settings

[barcoMeCasa]

Just did a 6 day passage from Portugal down to the Canaries solo running openplotter on a raspberry pi3. Worked great, openplotter on a Pi is rock solid, watchdog plugin very useful solo for wind & off course alarms. Radar plugin great as well, but.....
Struggled a bit with the gains for the alarm settings. Difficult to set as there's nothing out there apart from a very occasional ship so hard to know if there gains are too low. Auto gain had alarms quite often so no chance of sleep, and of course I didn't record what settings I tried
Think gain was down about 35%, light airs so slight seas. But no smaller boat traffic to know if they would set off the alarm. so... any fellow single handers out there with a Halo+? What gains to you use? Or any other handy set up hints for the Halo?
I had guard zones set between 1Nm & 5Nm, so any target between those distances would set off an alarm.
The ancient sl72 I used to use seemed less likely to set off false alarms, though maybe I've the Halo set much more sensitive.

Any useful tips others have picked up along the way very welcome

Apart from that, Pi3 was just great, lots boat data on a web page on mobile phone & vnc into the Pi from a tablet so easy to do a quick check of everything from anywhere onboard, windspeed graphed very useful too. Opencpn runs 24/7 now in the anchorage with a waypoint/range ring to check the anchor/boat is where it was. New track every midnight.
TIA