Don you can trust Roger.
Here is the code
250.86 Exception No. 3: A metal elbow shall not be required to be grounded where it is installed in a nonmetallic raceway and is isolated from possible contact by a minimum cover of 450 mm (18 in.) to any part of the elbow or is encased in not less than 50 mm (2 in.) of concrete.
I must do this quite often while running underground conduits.
If it is the sweep breaking the surface I simply continue with EMT or IMC to the enclosure to get the sweep bonded.
If it was me I would not plan on a tugger for this pull. I would plan on plenty of wire lube, a good rope and 3 people minimum by hand.
Two if pulling it with something else, we will use anything that drives (slower the better) to pull cables in.