tpelc12,
WELCOME TO THE AWS WELDING FORUM!!
Depending upon the size and schedule or wall thickness of the railing D1.1 more than likely does not apply. It will fall under D1.3.
Besides that, Stainless will be controlled by D1.6 and not D1.1 or 1.3.
Next, you say you qualified to 3G...that means you qualified to vertical (probably up) and so can also weld horizontal and flat. But not overhead. Doing railing you are more than likely going to have overhead welds that need to be made.
Finally, if you have not used any 7018 since you passed your qualification test back in July, then it expired in November and is no longer valid.
And that doesn't even cover the issue of rather it transfers from one company/school to another. In most cases it does not.
THUS, You are totally out of the scope of being properly qualified for the job at hand and are in need of being certified for the work at hand.
Have a Great Day, Brent