You offer some interesting ideas. I have a piling/post bumpers like the one you have shown (mine are nailed to piling). The piling (actually double pilings) are somewhat flexible which help absorb shock loading from impact against them. I think my real damage would come from the boat rocking 2+ ft. up and down against the piling before I can get my windward lines over and get the boat off the piling. The 12 foot padded connector board is especially interesing...depending on the hull shape, it might be mounted low enough to function, without hanging on the rubrail as boat moves up and down. This one that would have to go before the marina committee. Also, adding a second buddy line on leeward side, as suggested by others, is an alternate concept. But both have the boat rubbing it's sides on a fixed object.