2014 tacoma here with a swift and a flatbed. I'm running 35" tires, front bumper and winch. Old man emu heavy rear springs and airbags. Also did the 4 runner brake upgrade.
Drives great and I typically only loose .5-1 MPG with the camper on.
Engine braking is your friend on long descents
One thing I would certainly add on any heavy tacoma is a trans cooler and a way to monitor temps like a scan gauge or ultra gauge.
Its crazy how fast temps drop with the cooler when you let off it for even a few seconds. Only way to know is with a monitor.