Simple math, but have to have the actual weight of the Taco and Trailer/Boat in order to do that simple math
Here is the GVWR & GCWR ratings per the link provided
Here is the tow rating as per the link provided
Take the GCWR and subtract the Taco's actual weight, loaded ready to go
That will be the REAL MTWR (max tow weight rating), as the above tow rating from Toyota is with a 'curb' TACO, which few people will ever order
For those who think the OEM's MTWR is an absolute...take the GCWR and subtract the curb and it will be very close to the listed MTWR (there are other things in there, like the WD Hitch system and one 150 lb driver)
{edit}...of course the above charts only matter if you believe in the OEM ratings system or not...
-Ben
Picture of my rig1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...