Unless the spikes are not doing their job by fully supporting the speakers its not an issue if the speaker bottoms touch the carpet as long as the weight is carried by the spikes. If not then a cheaper option would be to get longer spikes any machine shop can turn some to your size requirement and they will not be expensive as the metal stock requirement is low and the machining is minimal. just bring them one of the originals and they can duplicate but adding length as needed, probably a 1/2 or so more is all you’ll need and they will look factory original.
if your looking for isolation there is a lot of choices from inexpensive to outrageous a quick google search under speaker isolation will bring up many. I just did a bunch of looking for a turntable project I just completed. couple that come to mind are:
IsoAcoustics, can do custom heights
Townshend audio, great stuff
there is a couple to get you going but there is literally 100’s of different types out there.