Yeah, def. don't try and stick weld those flimsy little gussets the factory puts in there. You will just melt right through it.
On a side note... tig is the best way to weld on a frame. cleanest and best looking welds, also strongest. But you have to have some experience with a tig. Its not a welder you can just sit down and learn with, you have to have some kinda training or a lot of experience with them to do good work.
Wire-feed is the way I would go if I didn't have access to a tig. MIG will def. be easier than a stick welder on your frame. Start with your voltage low and work your way up until you find where you need to be. You don't want to be burning holes through your frame all the time, then you will have to worry about fixing those. What a mess that would be! Remember, if your voltage is low the welds will just pile up without penetration. You can always grind off and clean it up if it piles up, but it will be more difficult to try and fill in a hole you burned through the frame. And you will be making a weak point. I usually have my voltage regulator on my miller set at 20.3volts if I am doing wirefeed work on the banshee frame. Feed Rate is just a hair under 4 on the miller unit I use.
Take some pictures of your welds and we cna give you advise on what to change to do better if needed.