Let me get this straight.
You have been towing a 5ver with a 3/4 ton diesel.
5vers are known for towing very well. And 3/4 ton diesel trucks are generally known to be good to great TVs.
Now you want to go to a run of the mill 1/2 ton with amenic 3.42 gears, and TTs that will exceed some or all of the TVs ratings?
Should work fine, I mean what could possibly go wrong.:B
Seriously, if you reread your OP, it is obvious that this is a bad idea.
Even if you could do it, (and I suspect there are some that do) you will not be happy especially since you have been used to a 5ver with a 3/4 ton diesel.