Raised Bed Positioning
If your bed is not shaded, the distance from the border will not make too much difference with regards to the plants you grow. You may find that some of the border plants will send their roots into the raised bed in search of the better soil, particularly if they are growing in poor soil. It may be a good idea to put a liner into your raised bed to prevent this, if you have not already done so.
I would make sure that you have plenty of room to move around the bed when you are tending it. At the kitchen garden, we have beds near to hedges and fruit trees and the minimum pathway around the edge is enough room to put a garden track. These are 39cm wide and this is plenty of room for me to carry out planting and maintenance.
Good luck with your raised bed gardening. Please let me know if I can be of any further help.