if you are going to sell items to the public there are certain liabilities in doing so. I doubt you will have anyone sign a waiver to purchase your products, as that would most lkely raise questions to start with. Discalaimers would be the route I would pursue.
If you are only going to do some small runs of bumpers.... I doubt a LLC is affordable, but is worth doing to protect your personal assessts. Of course I would get legal advice from a lawyer rather than here on the forum.
I'm no lawyer either... For a small business with a small production run I think your options are going to be slim....would certainly get legal review of a a disclamer and include that in the receipt paperwork. These business obviously have discalimers for a reason, and I suspect that many of them are LLC business types. A disclaimer is nothing more than something that says if the product is used outside of what its desigend for...then the seller claims to have no liability for such use by the buyer.
You can't say..... don't use the bumper as a bumper and if you do I'm not responsible.
I'm guessing...on this but I suspect that in most cases with these type products (4*4) modifications and equipment bought and installed by the consumer....that the point of sale would claim that the user improperly installed the item or operated the vehicle in an unsafe manner...thereby incurring all liablity themselves... by their own "dangerous acts".
The "for off-road" use is most likely a statement that deals with the crash standards etc that apply to vehicle bumpers... so ie.. if truck operated purely off-road then those standards would not apply and if the consumer operated the truck "on-road" they assume all related liablity. Which obviously applies to many more items other than a bumper.
"joe blow" just can't start selling items to the public that relate to vehicle safety (bumpers, brakes, air bags, seat belts...etc) and not go through some R&D phase, safety phase, most likely some type of certifiation by a PE engineer etc and probally some type of certifiation throgh a certfied professional engineering shop, that's where you have to say for opertion off-road only to partially cover your @$$!
Another good statement is "install at own risk, operate at own risk, modify at own risk" or words that have same meaning.
Thes words in these disclaimers and warranties and etc... are there for a reason and are carefully vetted by some lawyer.
I don't think there is a 100% bulletproof solution to legal liablity. You can be sued for just about anything at any time, the obove paer docs... attempt to limit your liablity exposure along with the setting up an LLC.
Any sane person in the 4*4 aftermarket business would have some type of disclaimer in place before the first sale takes place(after obtaining legal review), and I think should logically look at what it takes to setup an LLC, or consult with a lawyer as to personal liablity exposure.