I am surprised about the comment you have trouble with an 8% grade. I can easily maintain 70mph at even the steepest of hills here again loaded & unloaded.
On that basis alone you'll like the 4 Runner better as you can more easily modulate the throttle on an incline without worry about slipping the clutch.
I keep a spreadsheet of vehicles, with various notes; one of the big things I take note of is hp and torque curves, and gearing. Best I can tell is the following, for breakaway torque (torque at 2k rpm convertor stall speed, times 1.8 convertor multiplication, times all gears, divided by tire radius):
RAV4 I4: 2755ft-lb (the current 2.5L)
RAV4 V6: 3610 ft-lb
4Runner 3.4L V6, 4.10:1 gear, P225/75R15 (non-31” tires): 3330 ft-lb
Silverado, 3.23 non-towing gearing: 4.3L is 3240, 4.8L is 3645 and 5.3L is 4050 (torque taken at 1800rpm)
Silverado, 3.42 towing gearing: 4.3L is 3431, 4.8L is 3859 and 5.3 is 4288
Silverado, 5.3L with 6spd Allison and 3.42’s: 5634
And my TDI, chipped or unchipped, won’t make a difference as I’m not going to dump the clutch at above 2k rpm, and the turbo isn’t doing much below 2k anyhow:
At 1200rpm: 1839 ft-lb
At 1500rpm: 2122 ft-lb
At 2000rpm: 2504 ft-lb
Once going the TDI is great, although it can suffer in the end from lack of hp (although a lower curb weight helps a lot with that). I’m in the process of getting it chipped (260ft-lb and 150hp? Something like that) so it will now pull its 1,500lb rating with ease. But I’ll still have issues with start/stop on a hill. That 1.8 gain factor in a convertor, plus its ability to shed heat, is a major factor. If only I had a creeper gear!
From what I can tell, the following payload (low-drag pop-up camper, plus weight of driver and passengers and junk) applies, assuming 8% max grade:
RAV4 I4: 2,500lb total
RAV4 V6: 3,500lb total (only because at 60mph on anything over 8% will downshift to 2nd and spin at 5,600rpm)
3.4L 4Runner (4.1:1, 225/75R15, auto): 3,500lb
4.3L EC Silverado, 3.42’s: 2,500lb
4.8L EC Silverado, 3.42’s: 4,500lb
5.3L EC Silverado, 3.42’s, 4spd auto: 5,500lb
All of these require near full throttle, in 2nd gear to do 8% hills at 60mph. Slower speeds required for steeper hills, or in high terrain. Only the V6 RAV4 might stay in 3rd on the less steep hills. My stock TDI, at 2,500lb payload would not pull 8% in 4th at 60, and 3rd won’t help. Once chipped it’ll pull 2,500lb with ease—but again be limited by the clutch at takeoff. [And my towing goals at the moment is about 460lb of people, assume 500lb stuff, and my small pop-up is 1,000lb dry—that gives me a 500lb fudge factor.]