Extra Fill, But Not Topping Off

[bowtieguy]

well, my experiment w/ ethanol free gas is apparently over as i tested the gas positive for alcohol.

so, i have a question or 2 about filling up. i delayed this technique during my testing, but here it is...

i like to get an extra gallon of gas when i fill to get me thru 2 weeks, so i fill EXACTLY 1 gal past the first click. can this damage my sending unit? and does this skew my FE log(or MPGs)?