you can register a pickup truck in NY for any weight you want to. your registration fee corresponds to that weight. i know of poeple registering 1-ton dodges (late 90's) for , 35klbw so they can legally pull JD 650 foresty dozers on triaxle trailers. its wayyyy over GVW or whatever, but the state does not care, its only about $$$. there're reg fees are much higher, but thats all the state cares about.
why cant i have a 1-ton, diesel powered, non-commercial service truck? maybe i enjoy tinkering with older dodges (i have 5), maybe i like having a convenient place for storing tools, chainsaws, fuel, straps, etc, maybe i like having a heavy duty truck for towing my personal trailer around, maybe i like having a dirt-simple engine/trans/truck that does not have controllers/computers/$40k price tags? Nothing illegal in that.......
as for horse show people: it seems a majority of them (and i am NOT a horse guy, several in my family are) tend to have big pickup trucks/big trailers/"motorhomes"/ "private" semi trucks etc. these are all considered money making vehicles, since they are 99% of the time showing horses in an attempt ot win prize money or some type of prize. sometimes, the driver of said truck is not "classed" to drive the truck they are driving (
i have seen this happen, and had to go finish the trip b/c i have a class A). horse people seem to have a different set of rules they they adhere to, but is not legal. ........just what i've seen..............
kinda like guys with HUGE bus-based RVs that dont need CDLs or air brake endorsements to drive (you know you've seen them-shouldnt be driving a civic, much less a 50klb bus "RV"

). same with race car guys; some think they can register a freightliner truck as non-commercial or RV, haul a 53 triaxle race trailer, and no rules apply to them ...there IS a double standard between commercial/non-commecial
clearly, YMMV, as mine seems to from others. i have never registered a pickup as commercial in NY. i am pretty sure "downstate" NY has very diffent rules that "upstate" NY. also, i am NOT hauling for profit, so any commercial regulations do not apply to me