[Cob] mixing method

[Bob Smolen]

I am completely new to cob , but would like to build a small building using a combination of timberframe and cob or straight cob. I have land which is primarily calssified as dubuque type silt loam soil. The subsoli contains very sticky clay and no sand. I dont have any problem bringing in sand from a nearby sandstone/sand deposit which I used as a base for my shop concrete base. My dilemma is how do I mix this clayey soil with sand and straw. I am getting too old for the manual mixing pit and pitchfork. I do have a skidsteer (bobcat) and a cat for clearing the top soil. Has anyone used a landscape tiller that attaches to a bobcat. I could rent one and possibly break up a large quantity of soil which I would cover and later mix using the bucket on my bobcat.
Do you think this will work? Are there simpler mechanical methods? I dont have a concrete pad but could have one poured next to my shop as it could be used later for parking equipment or other uses. Is a rototiller very good?
Thanks,
Bob