in our line of business, people refer to items with many different names i.e., I've heard a shackle referred to as "clevis", etc. I've never heard this called a tied rod before, as our industry refers to them as turnbuckles. That's not to say your reference is incorrect, just the first time I've heard it.
Would a single lock nut be enough to keep it from loosening?
Yes, a single lock nut would be sufficient. The manufacturer of the fitting sends two so it looks symmetrical.
That’s a tied rod not a turnbuckle
in our line of business, people refer to items with many different names i.e., I've heard a shackle referred to as "clevis", etc. I've never heard this called a tied rod before, as our industry refers to them as turnbuckles. That's not to say your reference is incorrect, just the first time I've heard it.
A screw driver will do it just fine