Tanner,
no mild steel does not have to be tigged.
the ones I installed were the tube versions, I think it looks less of an add on. they were 4130, tigged, and 8 of them. Figure a good 1 1/2 to 2 hours apeice to fit and install, depending on what the chassis shop charges, could be 500 to 800 bucks. I think I charged the guy 600 or so, but there was stuff to dismantle, then reinstall, chassis was powdercoated so you gotta clean that off where you weld to.
mild steel would go quicker and a little cheaper.
The plates would be easier and quicker to do, and if you got a mig welder, and can use it, you can do it yourself, or fit the plates and take it somewere to get welded.
I have some pics here somewere I can email to you, I havnet figured out how to add pics yet here...