Hmm there is certainly some food for thought coming through! I sent the photos requested off at the weekend, so we shall see what they have to say.
I think the main use will be getting a weekly shop with my daughter on the back once she has outgrown her copilot seat, so hopefully there wont be an enourmous ammount of weight to deal with.
Don think I can get away with geting another bike to do this with as the wife thinks 5 is quite enough...... So the option of buying a cargo bike and fitting a motor is out
I will make sure I look at any way to secure an axle connected trailer as well as that is what my LBS guy was trying to push me at the weekend.
Thanks for your thoughts so far guys!