I'm laying out the components for the fincan area on my L1 now. I just drilled out the rings for adding the 24mm airstarts around the 38mm sustainer. I was planning on 3 centering rings: rear, front of outboard motor tubes, and front of main mount.

My question is: how far up to put the middle centering ring? Since I'm going to replace the thick plywood fins with .062 G10, I can make the TTW tab any length along the root. The stock tab doesn't go all the way to the leading edge of the fin and that seems iffy.

The tradeoffs/options are:
1)full-length fin tab with ring at the front-more fin weight, more weight from long outboard motor tubes, very strong
2)full length fin tab with middle ring mid-fin - more fin weight, less motor tube weight, front of ttw tab not supported by ring
3)partial length fin tab with middle ring mid-fin - lower fin weight, less motor tube weight, front of fin not ttw
4)?

I know this is way overthinking for L1, but I want to play with this one for a while after L1. Probably will cert with just an H and motor eject, but I'll have the capability to do DD and airstarts later.

If I felt the urge, I could do a T-T fibreglass and stuff a J in for L2, but at that point I'd rather start fresh.

Thanks in advance for advice!
-Ken