Towability has nothing to do with part time 4wd. The transfer case has to have a neutral position. Domestic trucks have available transfer cases with a neutral. Toyota trucks have not had a neutral position since around 2005. The tf is electronic with no neutral. They are part time 4wd. A driveshaft disconnect can solve that problem. You can download owners manuals and see what Toyota says about dinghy towing.
Moisheh