1/2 tank? Nah. Waaay too much.

I make it a practice to keep most gas out in my shed with the yard equipment, away from the house.
Most of my models hang from the ceiling or walls in the garage, which is attached to the home.

There's a safety factor here that too many ignore!

Just an ounce/1 ounce or less, in your models, will do just fine to keep things ready for the next flight.