I use an amped Riker UL3 (maxxed) but I'd bet a (maxxed) Breer M4 or 5 would be better, then ofc use an Opalo or a similar "small" eco weapon to finish.
Dunno where any really large untaxed spawns are, but Atami Paradise has a nice dense spawn to smoke those things. Tax there isn't unreasonable imo.
Tippin'