rookie mistake?
But if you messed with the adjusters, then the only way to figure it out is to follow the factory procedure and measure each side and measure again to be sure they are within spec. Also, did you over-torque the axle nut? That can put undue stress on the wheel bearings and might cause the squeal you are talking about. Loosen it, check for proper torque specs (you have the service manual right?) and torque to spec.
The belt tension tool you speak of is only required to measure deflection of the drive belt. That will tell you if it's too loose, or too tight. It won't help with wheel alignment however if you intend to keep your Sportster and put many miles on it, you should invest in the proper tool to do it.
This is the proper alignment procedure. My alignment tool is a piece of a metal clothes hanger that the straight piece has been cut, and the end bent down, as shown in the picture. Works great.



