I think the biggest problem is to get the anchor to hang in the right position as it is being lifted.
When Allan had an extended roller fitted on his Merry Fisher, he tried a number of different ideas to see if we could get it in the correct position to stow on the roller.
In the end I found it easier to winch it up until the anchor was clear of the water and then manual pull the last bit in by hand, this way I could keep the anchor clear of the hull to prevent damage if it start to swing about in the swell and if needs be lift the anchor shaft onto the roller.
It has been awhile since I have been out with Allan so he might have come up with a better method.
Not exactly what you wanted to hear I suspect.