Welding floor pan and rocker

[sgr60]

I'm getting ready to put in a floor pan patch and new rocker on the truck. I'm still in the measuring/planning stage at this point, and I noticed how close the fuel tank is to the area that I'm going to be working in.

With the tank right under the seat, it makes me nervous to be welding (and also grinding/cutting) right above it. Since this is a a very common repair, I imagine I'm not the first to have this concern. What have you all done to mitigate the risk? I suppose the tank could be removed entirely, but short of that, what's the safest way to work in that area?