I really don't think you need to. I had to cut mine back pretty severely on that side to clear the Magnumforce non-adjustable UCA's I have on my Duster right now, they have a very tight "V" shape. I haven't had any issues even running 275/35/18's and 1.12" torsion bars. The top corner of the tab isn't doing much strength wise for the mount, the lower corner and leg where it's welded to the frame is the important part. Plus that's the side that's continuous with the shock mount. A gusset wouldn't hurt any either, but I don't think it's a "must have" situation especially for a street car.
It is a super handy skill to have. There are some pretty inexpensive MIG welders out there now that would still do just fine for some occasional work. I would want a gas set up so as not to deal with the flux core thing, but even then you can get fairly inexpensive machines to do that. A 110 welder can still get a lot done on these cars if you're not going crazy with chassis stiffening. Even if you are, just have to watch your duty cycle. And a lot of JC's offer intro to welding courses that are pretty inexpensive and super helpful for a beginner if you don't know where to start.