Jafant...
My current pair of 3.5's did not have the spikes included so I simply used some isolation blocks to raise them to the appropriate height having them would have provided. The pair I gifted to my nephew did have them so I could measure.
I've never seen a pair of this model with outriggers anywhere so I have to think they were not designed for use? A common issue when buying this model now is with the spikes sometimes as they tend to bust the plinth where they screw in, no doubt from attempting to reposition 'em without lifting them. They're relatively heavy so that's understandable.
This pair did not experience that problem so if I come across a set of spikes somewhere I'll buy them. Not a real issue at all for me.
Imagine getting these for $350 like I did - from a fellow member no less. Easily my best ever purchase.