Tips for Boon Duration
Not easy. You have a minor trait in chaos which increases boon duration for each boon you have on you, but you rarely have many boons on you out of combat (basically 2 with the signet, which means + 6% boon duration). So to get 100%, you have to go for the runes (and/or Doubloons) and/or food.
An easier way is to also have focus and use focus 4 when the signet’s swiftness is gone (and remember, focus 4 does not stack swiftness, you have to wait for the signet’s swiftness to fade before using focus 4).
100% boon duration is going to be tough. You might be better off settling for a power-based phantasm build with centaur runes for the swiftness.
Or just use the focus every 25 seconds. By running over the line once, you’ll have more or less permanent swiftness between that and the signet.
In my experience with runes of the pack, focus, and sigil of inspiration with a bit of boon duration food, running over 1 temporal curtain keeps near perma swiftness up for a good 30 to 40 seconds without having to constantly time your curtains right between signet swiftness refreshes.
The signets passive is able to maintain swiftness on you for quite some time with this set up.