I've installed nearly every type of header on the market. For me removing two subframe bolts and being done in 20 minutes with the rear header is the best way to go. Doing the dipstick in the car loses trans fluid, makes a mess etc. My suggestion is lower the subframe.

As for getting SD's together. This is a series of light taps with a rubber mallet while tightening the front up. Takes almost no time and is done.

Average set of headers takes me about 2-3 hours complete