Evap leak 2001 Ford Taurus from Ohio.

Hey scotty hope is well,

I just bought a 2001 Ford Taurus with 177,000 miles on it. I spent about $1,000 but Im a little worried. The cars engine light came on due to a e-vap leak. There is also a door signal light on the dash as well. I did first put on a new gas cap, reset the engine light it worked for 3 days as long wuth the door signal light but both came back on. Took it to the dealer and they smoke the car to see where it was coming from. It showed that the canister needed to be replaced in the back of the car. They smoked the car again and found another leak on top of the gas tank. They want to put a whole new gas tank on the car for another 1,000. The dealership says there is a lot of undercoat that the previous owner put on the car and they think that they might be hiding something. I wanted to know what would you do in this instance? Do you think maybe a slight chance its a fuse Im not good at cars but I only thought cause both cane on at the same time. Thank you very much