If you have to keep it that short there are three clamping methods
1. cut a Short piece of hose, expand it with a set of forceps or small needle nose pliers and slide the fuel line in that piece then put it back on the tank.
2. use a small cable tie on them and pull them as tight as you can to clamp the tubing on the nipples.
3. wrap a piece of single strand wire around it and twist the wire tight but not tight enough to cut the hose (this take practice)
any of those work well, I have done a few planes where the plug and tank nipple have extended through the fire wall and not had a lot of room. Like putting a 120 in a 60 size war bird, 100 on a magic extra, etc.
Have fun flying your toy when you get it done.