Is there a way to measure current and fault current better than the ACS716KLATR-6BB-T
When you say 3kV of isolation, is that your working voltage because the ACS* line are only spec'ed at 870Vpk and are dielectric tested to 3kV for 1minute.

As for space... THe ACS* from Allegro are quite compact and provide a reasonable compensated output. You will generally not get a smaller complete package.

Depending on where you are space constrained one alternative you may want to consider is a Hall Effect sensor placed over the current carrying trace (with suitable material to provide ISOLATION.  

This however will require a current source (5mA) and at least one instrumentation amplifier to produce a suitable voltage output. Overall this will require a lot more real estate than a SOIC16, but you may be able to realise a more suitable physical layout.