I like so many aspects of this bike. Cruiser frame. Front suspension. Shift kit. It looks like a very well done installation.
The only thing I have trouble with is the plastic reserve tank on the front. That strikes me as being very very dangerous. Most serious accidents are front end collisions. Can you imagine what would happen in such a scenario? As the plastic tank is crushed between the bike and the obstacle the gas is sprayed everywhere including on the rider. One source of ignition from something like a hot exhaust and you have a fireball with the rider in the middle of it.
If you move the tank anywhere but the front the chances of this happening are much much lower. If the tank is made of metal then even better.
You are correct. It is easily fixed. Even a metal bottle would be vastly superior to a plastic one since it wouldn't be so inclined to spray fuel everywhere in an accident. Something like this might work, Brunton Fuel bottles
Naturally the best place for a tank is on the back.
It is one thing to build a custom bike and then ride it yourself. Things change a bit when you start to sell your creations to others. As builders we have a responsibility to make things reasonably safe.