don't know about building boxes for SFG; you might check on the SFG forum.

The teepees need to be sturdy enough to support whatever kind of vines you're planting on them.

Grapevines, for instance, would need a heavier support than peas.

If your poles are thinnish, you can set them closer together.

I don't think it's critical;
if the poles are as big around as your thumb, they're probably plenty sturdy for teepees.

I've seen bamboo fencing, & it's very nice, but I think you have to string it together with twine & tie knots between each pole, sort of like stringing pearls only with at least 2 rows of strings.

Best luck, & have fun!

If you think a buffalo hide teepee was only supported by poles stuck in the ground and meeting at the top center, well maybe you are right. But I think I saw drawings showing they also had supports going around in a circle linking the verticle poles together for strength.

I got a couple dozen bamboo patio torches at a church sale once. Still have them tucked away waiting for the right spot and place to make a type of teepee with the poles (sans torches). I will probably reinforce them like I stated above and then use nylon stockings to help support next years squash in a verticle setup. Might work.