Poly Gas Tank Modification??
 

I have a poly tank for my project that has the fuel fill all the way aft. The molded fill is pointing up at about 45 degrees, it's a little too tall and it turns out that it's gonna hit the bottom of the deck. I would like to remove it and relocate a 90 degree fill a few feet forward to better align with all the stuff I have going on. The factory plate in the top of the tank is big enough to fit my arm in to work from the inside (thinking nuts for through bolt!). I have seen poly tanks with bolted on aluminum fill fittings but I did a search and didn't come up with anything.
1. Is it realistic to modify the tank in this way?
2. Are there retrofit fill parts available?

Thanks.