Welcome to the board and to the world of Toyota's.
The answer to your question is yes, there were 1 ton versions of the '84-'88 truck body styling, which is known in the 4x4 world as a 2nd gen, do it being the 2nd generation to be sold as both 2wd and 4wd, 1st gen is '79-'83.
The information you found about 1 ton Toys coming w/dual rear wheels is also correct, all single wheeled rear axles are half tons, the larger spring pack was likely built to support the heavy flatbed. The factory 1 ton wheels have 6 on 8.5" lug pattern, and were normally sold as with matching front and rear, as on this truck here
Though, it appears that the conversion market, mismatched them, as the 2wd motorhomes come with the larger lug pattern, as well as the rear 1 ton pattern and standard 5 lug front, and the 4x4 version with the rear dual wheels have the standard 6 lug front.
Outside of the dual axle, and the larger wheel pattern on the front of 2wd's, everything else on the 1 tons and 1/2 tons is the same.
