If you did it yes, they would stay on the ground. Your center of gravity would drop as your wheels would probably weigh more then your vehicle. Have fun driving them though. Not to mention all the water sloshing around.
The easiest solution for extending the axles is either longer springs or relocating your spring pads on your axle. If you want to really spread it out, your best bet is probably a coil over solution.
This is optimum because on the front your steering is the furthest item out, and on the rear it is simply your spring mounts. Take a look at some Buggy designs to see how switching to a coil over solution will make spreading your wheel base a lot easier.
If you want to keep it simpler, the Missing Link setup from Trail Tough for running Jeep YJ springs is a solid way to extend the wheelbase a bit while not doing to many modifications. Or you can do the Rear Spring Up Front/CJ Springs in Rear conversion.