Truck bed coating will probably dry too rough and wont sand & smooth easily... and will look like crap after that.
Wheel covers might be ok for a while... but the intensity of arcade machines is 1000x that of driving a real car. They will get dirty, and eventually get torn off / ripped up... more than likely. Also, being a 360 degree wheel... its possible it could throw off the balance of the wheel.
Ive heard Plasti-Dip stuff is a nightmare to work with, and gives poor results.. and, its not very durable.
Bondo essentially IS plastic. But a much more workable version of it... where you can easily sand and paint it. And epoxy paint is essentially epoxy... and we all know how tough epoxy can be. Being in spray form, makes it easy to lay down many smooth flat coats... and no clear-coat should be needed, as it will have its own shine.
If you dont want to work with bondo... they do sell a 2 part plastic epoxy based putty. The strongest / best one Ive worked with is by Quik-Steel (not Quick-Steel.. thats inferior). IN putty form, it may not be as easy to work than something like bondo however. You also dont have a very long work time with it. Its hard as a rock in 5min flat... and its so hard, that you cant even scratch it with a steel nail. I suppose a lesser epoxy paste might work fine, and be easier to apply. As again, you are just going to cover over it with the paint.
As for the bare metal, I might try to buff it out. Though, might be difficult due to the way its constructed.