Thanks! but the widebody design isn't entirely mine, it's a clone of the rocketbunny v1 kit, i'm using it as a baseline for my own since it has the right arch width to properly house 11J wheels with the correct offset, as well as the cut templates for the original arches to house the wider wheels.
As for how people run them, the common way is to simply cut out the arches and slap thick spacers on, personally I don't like that approach because the balance of the wheel gets fucked up because the weight point isnt where the wheel was designed to take the weight, thus puts abnormal pressures on your hubs bearings and drives.
The correct way, if there is such a thing, is to run wheels wide enough for the new arch width, with the correct offset, and, normally, running a stronger hub unit, in addition to that you could also run fully wider tracked parts from a compatible car to space out the hub itself so the actual mounting points shift, but that's more the approach you take when you're custom fabricating stuff and have the time/money to do it, generally most people who dont even want the extra cost of a new wheelset, will just slap thick spacers on.
Here's a 4K render of the model with a better environment in place.