That is something im always concerned about. Fjords is my favourite map because of the fact that it has a really high hight ceiling.
Then you have the map Dunes with a questionable Ceiling...
I don't profess to being a pilot of note, let alone a great pilot but this is exactly my experience when we faced this build flown by a captain that knew the guns arcs. They sat at the map height, completely negating the limited upward arcs. We got rushed, negating our lumberjack goldfish and taking out the balloon of one junker just meant getting shot to pieces by the other.
Ace's suggestion of reversing the arcs sounds good to me. As it stands, sitting at the map ceiling with triple artemis is very low risk. Lose your balloon? No problem, you have the maximum possible time to get it back up (especially when your other triple art junker just disabled/killed them as you descended). Having to hover close to the terrain to stop people flying under you means that if you lose your balloon, you're going to start taking hull damage, making a multitude of balloon popping builds viable.