You will still have the same issue with a solid axle ... There is enough play in all the components (including links) that adds up allowing for inaccuracies, even with a solid axle it should be done on the ground after rolling the vehicle forward!

I personally have done the line technique to many vehicles with far bigger mudders than you can fit on a PU.

But like you said, to each their own and as long as you are comfortable with the method thats all that matters.

Honestly any method has it's faults, It really boils down to how accurate your goal is, In racing we don't really care what the measurement is as long as we can consistently get the same measurement accurately.

-Enjoy
fh : )_~