wood in the ground was out of the question for me. was either some form of T post(there are many) or galvanized metal(fencing/conduit). way easier to set and will last far longer and plenty strong enough. these are the forces on the structure:
the trellis is facing N → S and is inside of a privacy fence but im more worried about the plants acting like a sail and “wiggling” the tposts loose. they are 2’ in the ground so not a huge worry.
hopefully that didnt come off as snooty. i spent a lot of time going back and forth on how i was going to design it and what materials i was going to use. it was also my first attempt at building a trellis and growing kiwis. maybe it goes up in 
if thats the case ill probably still go with metal but something stronger like fencing.