When you create your method statement make sure you include how you will use them, roped off at the top, footed at the bottom etc... this way as long as you operate within your proposed methods you are carrying out ladder work in a controlled and safe method.
When you send this ti your prospective client if they are not happy with this then they can question it with you.
I would also speak to your insurance company to ask what they require for your insurance to be valid