rockm
Spuds Moyogi
WIDE is better than multi-level. When you go multi-level, your trees on the lower levels back branches will get screwed up as they are either shoved up against the support behind them or shaded out. This problem increases with the size of your trees--If you have bigger trees, you will get broken or weak back branches.Geez...
You’re making this MUCH harder than it needs to be! Why do you need two levels? A single, relatively wide bench is much better. That way you can get to both sides of the trees easily.
BNut’s idea works, if you have to have two levels.
Here are the columns for my benches:
View attachment 319609
If you did something like this with concrete blocks, you would create benches about 24” wide. Wide benches are more stable. You can offset the trees a bit, one forward, one back so they don’t shade each other.
I used 12 foot long 4x6 posts as my surface. They won’t sag. 2 by lumber will eventually sag without a center support. You wouldn’t need a full column as a center support, just a single stack of blocks would probably be enough to prevent sagging.
But your setup is temporary. Maybe sagging doesn’t matter to you. Regardless, since it’s temporary, I wouldn’t mortar or glue anything.
I've never added levels to any of my stands, only increased their widths--wide is better...