I have purchased an 8X12 shed with the following floor supports; 2X4 joists on 16" centers, with two 4X4 skids running perpendicular to the 2X4 joist the full 12 foot length. Since I haven't seen Dek Block with 4" gaps only the 2" how can I make this arrangement work? Cutting the 4X4 down to fit doesn't appear as a viable solution. Thanks in advance.