I believe in doing the job properly and then you only have to do it once which I think is what JBT means

If you get a suitable lowered spring that is legal now and fit that, then you won't have to change them a couple of times.
The problems with those spacers is that if your aiming for 20mm then thats a lot of bolt you won't have and that can create a lot worse problem.
You could possibly get a cap made up incorporating a spacer in built that would allow for the normal amount of bolt, but that would probably be as much to get made as new springs.
good luck with which ever way you go.
Cheers
Dale
