I can't believe that those shops are that lame or don't want to be bothered! Probably low-performance parts replacers!(not mechanics, they would diagnose and fix the problem).
I used to own a tire store that did many alignments of all kinds of cars and trucks. Many racecars that were much lower than any street cars. Dirt cars, drag cars, road racing cars, lifted 4x4's, street rods. This is nothing that can't be fixed with a couple of 2x8's and a swift kick in the ass for motivation!
Unfortunately, there are many in the auto service industry that take a dim view of modified cars. They may require someone to think a little about the job at hand, use the theory that they were trained with, not just rely on the machine to show "green" in spec and "red" when out of spec.
I had the good fortune to have some mechanics work for me and with me to solve many problems relating to alignments. Our motto was "we fix cheap alignments here". We tackled rebuilt wrecks, race cars, even trailers!
You can take matters into your own hands by finding a shop that caters to lowered vehicles, take the skirts off and replace after your alignment, or round up some 2x8's and take them with you. Sometimes, 4 pieces short enough to fit in the car are better than 2 longer pieces.
I hope this helps.
Tony D
Graduate of the Hunter Alignment Training Course