It sounds like a good plan.
For the rear attachment points:
Depending on where the bulkhead is placed, there may be space to attach padeyes under the deck.
You could consider using Footman's Loops (padeyes), which are made specifically for straps and webbing:

My advice: Do everything you can to make the rear attachments 'non-elastic' to avoid having the backband under your butt when you enter the kayak 'butt-first'. That's the reason I dislike backbands so much! :-)

Do some temporary rigging and see what feels comfortable. With one Immersion Research backband, I found it was more comfortable 'upside down'.

You could check out some of the IR ratchet backbands; they make adjustment 'on the fly' easy with the ratchet mechanism. The ratchets are more durable in a salty environment these days, compared to the original brass/steel/white metal versions.
https://www.immersionresearch.com/store/paddling-accessories/backbands/reggie-backband/