I don't think modifying it is going to help your insurance.
I think the Freezer is right here, if your only 16 and undertaking a PS conversion you may be a little lightweight in the engineering experience required. I don't class myself a quality fabricator but I am an engineer and there is a shed load of things to take into consideration when doing this. It's not a simple case of chop the chassis and bolt the box, and it'll be ok because I can weld with my SIP migmate 140 .
PS isn't necessary anyway unless you're running massive tyres, the trick is to keep the vehicle rolling when turning the steering - it becomes alot easier than trying to turn the wheel stationary.