Amarok wheels, have about 10mm less of ET, so they stick out about 10mm further each side; so your need for spacers is lessened.
255/55/19 are way too big imo, unless you are changing other things. If they even fit in arches (with out a suspension lift). The drivability will be highly compromised imo.
I would even advise against a 255/50/19 size, but 255/45/19 would be fine.
A 20mm drop is perfect; or 30mm drop max.
No front splitter; its just too easy to rip them off on soft/un-made ground.
I've just changed to Amarok wheels; and really liked the look of the 19:"; but chose 18", because the tyre choices better imo (235/55/18); and the 19" just looked too prone to kerbing type damage, for the way we use our vehicle.
We use ours off-road nearly every weekend, so I've learn't the hard way over the years
Maybe consider looking at the leaving the stock springs alone and changing the shockers to Koni Active dampers
@CRS Performance
Please let us all know which way you choose to go