I do what @svk does. Cut each round almost all the way through all the way along the log while the chain is sharp. Then nibble through very gently in about 4 round sections (or whatever I reckon I'll be able to roll with the log jack), roll then finish them off. I figure I'll be resharpening anyway so I don't mind so much if I touch a little dirt at the end of the process. If there's a big fork that I won't be able to roll, save those bits for last. Noodling in place might be an option if you have already done the cross cuts and then you might be able to split the bulk of the weight from the fork and you might be able to manhandle it then.