You cannot buy a pier extension for the AVX. I found this ingenious idea on Cloudy Nights forum. It worked so well for me I thought I would share a simplified version with easy to follow plans (I hope). Here is a link to the PDF of the plans. I have never used Google Drive so I hope the link works. I would be happy to email the plans if it does not work. .
https://drive.google.com/open?id=0B4-4zSLiWsKKMUotV0lLc251SVU
https://drive.google.com/open?id=0B4-4zSLiWsKKMUotV0lLc251SVU
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