You can tow anything you want, but if something happens repairs are up to you. Honda only approves and warrants the CR-V and Fit as towable four down. It there's any factory warranty left you would lose it on the engine and trans if towing four down. And the shop people do look for towbar attachments and wiring added.
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '05 Odyssey