Creating a simple wheel

I have been trying to get a simple wheel that doesn't need to be very realistic, it just needs to work reasonably in almost all situations. I need it to: -to work if some of the other wheels of vehicle are removed -to work if mass of the vehicle is changed -to work if it is placed in a weird orientation(ex. on the front such that it kind of climbs walls) -preferably have some steering -preferably have no limit(wheel colliders have a 10 axle limit) but i can work with the limit if i have to -preferably have collision from all sides

WheelCollider: -doesn't take changes to stuff like the number of wheels or mass of vehicle well at run-time -can't be placed in non standard orientations as far as i can tell -doesn't have collision from all sides -10 axle limit(might be a problem for some larger vehicles

Because I don't really need realism i figured i would just used a cylindrical rigid-body that is attached to the car via spring joint and have it apply a certain amount of force distributed over the contact points which kind of worked. But Unity 5 no longer supports directional friction which basically prevents me from having the wheels slide forwards without also having them easily slid sideways.

a lot of these problems originate from PhysX 3.x(such as the no directional friction) but in unity i don't have some of the features that i could use as work around so i am kind of stuck so any suggestions