I can only advise that I find it much easier to work when I have a defined line I am working to. If you can draw at least a rough, oversize shape of what you want on the steel with a permamnent marker you can work faster to get the basic outline, then adjust and fine tune from there. You will have to re-mark the lines from time to time, they usually rub off after a while.
Trying to profile with a just a file is going to be an excersize in patience any way you do it. If you can use a hacksaw to at least take corners off where you have a lot of excess material, you will save yourself a lot of time. With some practice and creativity you can use intersecting cuts to remove metal in places most people would think impossible to get to with a hacksaw. Add a drill press to this and you can do even more by drilling metal out in places where the hacksaw won't work.
If you can get set up with a small portable bandsaw at some point in the future you will be able to profile with much better efficiency. In your situation this is probably the most cost-effective/least messy/dusty power tool you can add to your setup. The metal chips are too big to go airborne so they mostly just end up at your feet. I know this is probably a ways off for you but maybe it is something to look ahead towards. This would allow you to get 70-80% of the unwanted metal out of your way in a hurry compared to what you are doing now.
Harbor Freight sells one for around 80$, I'm not sure how well it performs though. Better than a hacksaw I would bet. I have a Porter Cable which cost around 280$ and works very well.
For a "stand" I have a small piece of 2x6 bolted to the frame of the saw that I just clamp into my bench vise and it becomes an instant bench-mounted bandsaw.