Stringbob
I attached the LGB track to the trestle deck with small exterior grade decking screws which has held the track very tight against the deck, using the preformed holes in the ties to place the screws.
Southern Colorado Marx Flyer
The bents are the upright and vertical supports for a bridge which are normally made with exterior grade wood cut to fit for outdoor use, along with screws or small bolts which can be a project in of itself. These bents or upright supports are molded in one piece out of PVC that look just like the wooden versions but are rot resistant and can be painted as well as glued with PVC cement...Personally, I don't think they would look out of proportion with O scale with a wider deck applied on top to support the track, that's why I mentioned it as a possible time saver that has worked very well for me.
Here is a link below to one of the many suppliers of this product that is made by Split Jaw, who also is well known for their rail clamps in the G scale community. You can also buy them direct.,They also make roadbed of the same material. However an eight foot piece of PVC fence material ran me around $8.00 which is a fair alternative. The bents come in a variety of sizes. Mine are a foot high. Hope this answers your question.
http://www.reindeerpass.com/sp...tle-bent-6-high.aspx