Vic: Since you are making your blocks, you might check the overall stacked up height of your block and cross sill. If the frame is perfect and not tweaked at all, the cross sills sitting on the blocks should be exactly the same height as the rear sill mounting brackets. That way the wood will be exactly flat and all mounting points will support the bed equally. If the frame is a bit bent or distorted, you may have to adjust some of the blocks up or down to make the bed sit flat. If you have a long straight-edge you can verify that all the cross sills are flat and the same height as the rear sill by setting them on the frame on their final resting spots and making sure the tops of the cross sills are all exactly level with each other.
Mar-Ktech
