Beto fin box repair

[SunSonCPR]

I am riding a Beto hand-me-down. I recently ran it aground and cracked one of the fin plugs. I would like to repair it myself but I am not sure the material of the board (PU or ESP). The board does not indicate one or the other. Does any one here know which make a Beto board is?

Also, how much work am i looking at to repair this thing? (photo attached). I have seen some repair instructions that require the plug to be removed completely and others that just do a surface repair. I would prefer to have a healthy balance of structural strength and lower time/tool needs. Would love advice on which avenue to pursue, thanks!