How are you running the Cat5 from your house to that if it's not attached to the wall? Do you leave the cat 5 exposed until it gets to the box?
For example a lot of my camera's will be under and eve but it's about 2FT away from the wall. My pig tail on my Lorex HD (Hikvison CD2032) is about 12". So i'm a little short. I was at home depot looking endlessly at the Cantex plastic boxes and the flex tubing and LB bodies trying to find a clean way of running my POE cams since I can't stand messy wires. I ended up get some 1/2 single gang metal boxes because there are more little parts, elbows, cable clamps, etc for them. Then running the 1/2 grey flex tubing to a LB body for the CAT5 then through to my house. It's a little overkill but I think it will look good. Then I can run 2 cams off the same junction box, by drilling the 1/4" hole at the top where the lid is and just clam shell it shut with a rubber grommet. So basically it's plumbing it for real electrical but for cams.
I would think the IP Cam manufactures should be selling or supplying these types of boxes/enclosures with their cams. It could be a simple clam shell like this below that would enclose the pigtail adapter and your POE cat5 on both ends with some foam or rubber gasket around the cable to keep out moisture. Then you can just secure it with a screw. I may have to invent something like that if it doesn't exists
. That is about in between using electrical tape and the full blown metal/plastic junction boxes. http://shoals.com/products/mc3-locking-clamshells/