I just finished installing two bunks 10 ft long on a trailer that I am rebuilding.I bolted the the two first the of 2x4's to the frame of the trailer about 30iches apart so that they would sit close enough to the bottom skids of my boat(wooden john boat).The way I did it was to put 2 bolts side by side on all the cross member's by drilling through the 2x4's and frame at the same time, to help make the bolt heads disappear( I chipped a 1/8 hole over the bolt spots with a wood chisel then drilled through and tightly bolted them to the frame,the bolts heads will disappear ei;sink in the wood)once I had my 2 first set of 2 by's bolted down I put a layer of PL construction glue on them then I put the other 2x4's on top and screwed the daylights out of them with 3inch deck screws this way I ended up with a double layer of 2x4's for bunks.Got my carpet from a carpet laying outfit' dumpster, cut them so I could wrap 3 sides of the bunk's and stapled them on the sides only,( with a hammer stapler its real easy).Is it good or not, I dont know? but thats how I did mines.. will see how well they hold up in the oncoming year...Hope this help's ....Mike freezing his a....s north of the border :wink: