foundation for load bearing straw bale

I'm hoping someone with some experience with building with straw bale can help me out with which foundation to choose. I'm building a small cabin- 13' by 23', and I want to go with load bearing to save on costs. My question is whether I should go with a rubble trench foundation with an earthbag stemwall filled with gravel, or with a wood deck on piers.

My slope is a 1 to 7 drop, so I'd have to cut about 4 ft on the uphill slope to get a pad to build on. If I went with a wood deck on piers I wouldn't have to do any excavating. It looks like it would be less expensive to go with the wood deck, and would possibly be better to keep the bales high and dry. Any other pros and cons to these two types of foundations? Thanks in advance for any input

Wood deck keeps the inside drier, too. Downside is the floors get cold if you don't insulate them well.

Good point R Scott. I picked up some 2" recycled rigid foam insulation for the floor. That will give me r13, but I'd like to get it up to r 30 plus to be comparable to the bale walls. I was thinking rigid foam under the floor boards (2x8's) and then fill up with loose cellulose insulation. Is this only for ceilings or will it be fine in the floor boards?