Bowti I have not seen this comment yet so I'll offer up my advice that my retired trucker FIL gave me.
When turning right move as far left in the lane you are turning from as safe to do and go deep into the corner remaining straight until your trailers wheels are passing the object then turn hard fast right making a "square" turn.
Follow the same process for left hand turns except bear as far right as safe to do before starting your turn in the same manner.
As far as backing up try, try , try again. Practice makes perfect. Well, Not every time even after you have done it for years I still got all muddled up once and a while.
I have a bootleg in my 100ft driveway that I have to back into. Sometimes first try is golden, other time it takes 3 or 4 attempts.