Help completing hole digging for deck posts

I am currently looking for someone to complete some hole digging for a backyard project I am working on.
I have 4 holes currently dug down to 36 – 40 inches. Need them dug down to 48 inches.

The options for completing the job could be:

– A small skid steer, with auger or other attachment
– Using a mini excavator to dig a few trenches down to 48″ (this would accommodate the 4 holes)
– Finish the job by hand with appropriate tools

I have limited space for yard access so a large backhoe would not be an option.

The ground consists of gravel, rocks and some sand. It’s not a fun job but will pay cash once complete.

Thank you.