How to season a carbon steel pan on an electric hob
To the question as asked: No, there are no more tricks. When you use the wrong tool for the job (in this case a too-small electric hob), then you can't expect the job to go well.
Nevertheless, there is an easy solution for you: Use the oven. If you are that worried about your rubber button, remove it before putting the pan in the oven, and pop it back in afterwards. But I use my own Mineral B in the oven frequently enough (and don't always bother to remove the button), and have had no problems with it.
I had never heard of the manufacturer's advise you cite, but if you absolutely want to stick to it (e.g. because of warranty issues) and are against the oven, you just have to live with a badly seasoned pan.