Used a 7/8 hole saw on mine right in front of the rear dog legs on the bottom. I then park facing up hill, stick the hose in the front dogleg access hole and turn it on. I then go start drinking a beer. When it's run clean for a few minutes I switch. To the other frame rail. I then finish my beer. I then out the hose in the access hole on top of the rear dog leg and make sure it flushes clear pointing both forward and back. I then do the same in the front dog leg. This process takes about 10 to 15 minutes. I then put a bar sprinkler under the front half of the jeep and go drink beer for another half hour or so. I then move it to the back half and drink more beer. Then I mount the sprinkler between the grill and the winch to clean the rad. After all that I wash the body making sure to flush the torque boxes and rear corners of any crap stuck up there. By this time I've had enough beers that I don't mind so much being covered in muddy water as inevitably I will get back spray on myself.

i do however plan to pickup one of those 90* bent pressure washer wands to help clean the under side with.
I coated the inside with the Eastwood internal frame paint and one day may add krown to it as well when I'm sure I have no more frame mods to do. (I suspect welding on a frame filled with oil may get interesting )
So far it seems to be working well as I haven't seen any rust coming out. I think the key is to not spare the water when cleaning.
—
There must have been a time
when we could have said no.