Think I buried 6 or 8. It was the same direct bury cable that I ran to my barn from the house and it was a good 200' and the barn box starts with a 60 amp main. I ran the RV post from that box with a dedicated 30 amp circuit. That was another 45'. With direct bury you don't need to use any hard conduit. I did run the cable in a 30' piece of 1" black plastic water line for extra protection for the section that ran under my gravel drive.
Forget the grandkids, the White Hawk is my mancave when the grands come a visiting and I've had enough crazyness. Flat screen, A/C or heat, fridge, coffee in the AM and a comfy lounge chair.
PS: in a pinch you can plug in a 15A adapter and run your weed eater or what ever.