Hey Charlie! For not loosing the screws you could put a hard rubber piece inside which takes up the vibrations. If this doesn't help you should use rubber+selflocking nuts+loctite and some of these little ones:
They are called Nordlock washer. Quite an intelligent product:
Normaly you only get them in a 100-pieces-box but KTM uses them for some really important screws eg. shift lever and you can order them seperately.