Hello again. This is not a typical house repair topic, but this forum has been helpful in the past, so I thought I would try again. I'm piecing together our wedding altar (just an arch) out of old 1x6 boards. Attached is the image. It will be about 8 ft tall at the top and 5 ft wide at the outside (interior arch with is 4 ft). I'll probably support it with a 1x4 frame behind it. The question I have is how to hold it upright. I was thinking about getting deck piers and then attaching a 3 ft section of a 4x4 to that. Then, screw the arch columns into that. I could probably bury the posts as well. The catch is that I'd like to do it without concrete because it will only be needed for the day. Thanks in advance for any ideas!