Treehouse ladder - 12ft and corrosion resistant from pressure treated wood?
For ground contact, besides the corrosion problem, there are general strength and stability issues potentially lurking.

Solutions include creating a concrete base, such as (from here):

Or pouring your own concrete base and incorporating post standoffs such as (from here)


Another issue is for whom is the ladder intended?  If it is teenagers, then your layout is probably adequate for all but the least athletic.  Otherwise, the ladder should extend above the deck for hand holds.