Hi,
The pads on my Spleene board worn out, so I want to replace them with something different. The Spleene has a surfboard shape, but it is thin like a twintip. I mainly ride the waves with frequent jumps and I jibe with every turn. I am thinking of getting a pair of surfboard tail pads (for the front and the back foot straps) and stick a 2-3 cm layer of foam between the board and the tail pads. I expect it to cushion those occasional less then graceful landings, but still keep it easy to slide the foot in and out of the foot strap at jibing, and give a good feel of the board at wave riding. I wonder if anyone has tried this? I am thinking of the closed cell EVA foams, but I am not sure what density would be suitable? Obviously it has to be firm but not hard, and has to keep its shape reasonably well.
Any ideas..?

You're right that a normal surfboard tail pad would do the job, you could use one at the front too, but I think a better looking option would be to get a sheet of this stuff for the front-
http://www.kitepower.com.au/catalog/product_17110_Surfboard_Deck_Pads_cat_355.html
NSI surf pads would be an option, I think you can get them without the inserts.
Bend your knees to cushion those hard landings and try riding toeside more instead of jibing all the time.