A block in the bilge is the way to go - but a raw wood block? I dunno -- I should think the wood block is too likely to rot. If were me, I would rather make an epoxy block, glue the block to the hull, then put the screw for the cable tie holder in the block.I have not had success getting stick-on cable tie mounts to hold in our boats. I use screw or bolt types now. One option is to epoxy a piece of wood to the attachment point, and then screw a mount into that.
DaCAP