So, he asked 2 simple questions and instead you told him what you think he needs. Is that because you were unable to answer his question so you felt compelled to tout your superiority by determining that you know better than he does? What kind of person does that make you?
Now, to answer the questions. There are stand alone fuel gauges available, the real question is will they be compatible with your sender? Perhaps a better solution would be to look at other models within the line-up of your 125's manufacturer and see if there is a speedo that will fit your needs. You did not tell us what kind of 125 you have so our help must be limited until we have more, better information.