Not difficult. Put firearm in case. Put case in car trunk. Close car trunk. You're good to go!
Before I met my wife she and her son had a small business and owned a couple of pistols. They ended the business and subsequently let the permits lapse.
Pistol carry permits are pretty much impossible for anyone except for retired LEOs. (Which is why there was a -- small -- group cheer coming from here when Kavanaugh was confirmed!)
If it's your home or your business, you still have the Constitutional right to defend it, even here in the People's Republic. Like North Carolina, permits are required to purchase pistols, but not to own pistols. (Yes, the paperwork is more complicated, by design).
The NJ 1966 Sills Act was rammed through 2 years before the 1968 GCA. Both Democrats and Republicans were responsible. The bill was passed in the wake of the Watts riots in 1965. The idea of armed insurrections among NJ's urban minorities scared the willies out of all the state legislators.
I personally have doubts that the 1966 bill is Constitutional. We will probably find out in the next few years.