I don't know if you can do this with the 550D, but with your 7D2 have you considered Manual mode with Auto ISO?
I use this method with my 1DX and 7D2 as it means that I can change settings very quickly without taking my eye from the viewfinder and (more importantly) without using my brain! If you go into Custom Functions, and assign EC (Exposure Compensation) to the "SET" button you can adjust exposure VERY quickly - handy for BIF and Airshows.
Using this setup my shutter speed is under my right index finger, my aperture under my thumb. So I just set the parameters I want and can instantly see if the ISO is within reasonable limits. With EC on the SET button any compensation can be set in well under a second without losing sight of your subject too.
It may sound a little daunting - but it is not, these days using my point and shoot is a MUCH more difficult challenge!
Unlike the 7D Mark II, the 550D (T2i) does not have the EC feature when you use Auto ISO in Manual mode.