Gents,

Tortured perfectionist amateur here. I am building stairs to an 18X40 deck I just built. The stairs will be L shaped with a total of 3 treads. One side will be ~9′ long and the other ~14′. I have read all the articles I could find both here, on Trex’s website, and several other sources. I have a very sandy lot in CT. Also, eventually I will be building a room where this section of deck is, but that may be 10 years down the road. (My garage is coming first!!) Here’s my challenge; I’ve read everything from:
1-Land the stringers on PT and let them float on the ground. 

2-Pour a 4-6″ slab. I did this on my other house in CT with a much larger stair case (18 4′ treads) and it’s 15+ years old and has never moved.

3-Pour a 4-6″ slab and haunch out under where the posts will land at the bottom 12″ deep.

4-Pour a 4″ slab with sono-tubes every 6′ or so.

5-4″ slab with sono-tubes at the ends where the bottom stair post will go and set the posts in the concrete. (I’ve always been told not to do this as it traps water and rots the post out quicker, but if this is incorrect I’m willing to change my mind)

6-(Mike Guertin’s method) Pour an actual footing 42″ deep along the entire stair assembly so all the stringers bear on the concrete. 

So considering that I will have the stairs in for an extended period but will likely pull them up at some point, is there a general consensus of what the best solution would be for my application? If Mr. Guertin’s way is best, I am happy to dig a trench. However, if a simple slab will do, it would make less work digging things up later. (New room will have a full basement so the footing would have to get pulled) Interested in your opinions. Thank you for any insight you might offer. I hope you and your families are all well.