Not getting into the usual insurance-vs-liability-vs-weight argument but here's a sampling of BC laws (where I live):
Maximum gross weight for tires
7.15 A person must not, without an overload permit, drive or operate on a highway a vehicle loaded or configured so that the gross weight on a tire exceeds either
(a) the manufacturer's rated capacity for the tire, or
(b) the tire load specified for that vehicle or vehicle combination in Appendix B, C, D, E, F, G, H or I.
Maximum gross weight for axles
7.16 (1) A person must not, without an overload permit, drive or operate on a highway a vehicle loaded or configured so that
(a) the gross weight on an axle exceeds the manufacturer's rated capacity for that axle or for the brake or suspension system with which the axle is equipped,
[en. B.C. Reg. 95/2006, s. 3.]
No doubt States have similar laws, I just don't care to dig.
The Op is over his weight rating from the OE if he doesn't have the trailering package.
You have a liability if you are knowingly operating a vehicle on public roads.
If an accident is caused as a result, you are liable.
If the accident is deemed to have been caused by a violation of vehicular law, you wanna bet the ins company won't deny you coverage for operating a vehicle in violation?
anyways, this is something that can go around and around forever and I've said my piece, so I'm dropping it right here.