rega P25:spacer with new mat?

I have a P25 with Dynavector 10x4.On the advice of my dealer i am using a 2 mm spacer with it.Now i want to upgrade to Ringmat Anniversary edition and know that it is thicker than the felt stock mat.At the same time there is no more space on my tonearm to install an additional spacer to even the arm up with the new mat .What should i do?
There is an extended lock nut that allows you to add another 2MM spacer. Music Direct stocks them.