I have made a drastic change to the side fill configuration on my 22 ft boat. Got rid of side fill for reasons unrelated to the problems I was having with filling. Your description of the fill spill problem is that it is hard to fill and it makes you anxious. Based on that description I do not know if your problem is the same as what I had. My problem was that if I filled slow and held the nozzle just so it might fill but it might spit back and stop. Before I totally got rid of the side fill I made a modification that allowed me to quickly fill to the brim (and beyond) but it was not EPA compliant. I can not recommend that fix in this public forum. I suppose I can recommend that modification for trouble shooting purposes only. Go up to the right hand corner and search using my name (DVW) and key word within content ‘side fill’.