I was trying to replace the stantion bases on my own - access, to say the least, was tight - so I put my inventive cap on.

The dob of grease sticks the nut to your finger - any washer can be stuck on top the nut - again with grease. By winding the cotton thread around the nut, when you have pressed the nut to the end of the bolt - simply pull on the thread and you can spin the nut to start it.

Did all six like this without a hitch. My set screws were quite long so I was able to hold them outside with small nosed vice-grips - these are great for awkward jobs - once started I was able to grip the nuts from the inside to finally tighten the set screws. Tie a piece of cord to the tool if there is a blind space below whatever access hole you have.