I haven't used the plastic bottles for storing gas lately.
I took a Berrymans B-12 Gas Treatment
tin can and drilled a hole in the lid so I could put a small piece of fuel line like used on a weed wacker or chainsaw through the hole and then I sealed around it with silicone.
I went on a 50mile round trip and figured I'd need a bit of extra gas to get back since I only had a 2L fuel tank on the bike, the B-12 can worked great but only holds 1 pint 16oz, in the future I will be making up some 16.9oz fuel containers from some energy drink cans I have collected, they are made from a very heavy gauge Alum. and have real good lids on them, I plan to drill the lids and install vent tubing in them like I did the B-12 can, I plan to make a rack that will hold 6 of the cans, this will give me around 3/4 of a gal. of reserve fuel onboard my bike that can be carried in a small space and safely.
pic of can included
PS: if you use plastic containers always make a vent line or you could get into big trouble if it burst form the pressure...........! very important to vent those fumes bro.