It seems to me that the seat is about the worst place to you can put storage except for on your body, doubly so when you are asking a dropper to move the weight. Lower your center of gravity and don't make the dropper push weight!
OneUp EDC with a tire plug and masterlink pliers is the lightest and most compact way to have all the tools (allens, T25, chaintool, and masterlinks). I put mine in my stem and use a super light Lezyne Pocket Drive HV (90g $30), but you can also get a OneUp Pump and put the EDC in the pump! If you pass through Summit and want to tap your steerer, I have a tap (install is redic simple).
https://www.oneupcomponents.com/products/edc-v2-tool
I strap the pump plus a Tubolito and lever to the downtube, what else could I need? I strap on a CO2 in that bunch if needed.
Garmin, food, medkit in frame bags... strap a coat to the frame if needed.
No packs unless I need more than the 1L I can put in 1-2 Fidlock bottles (then add my hip pack) or need to carry pads and chinpiece up the climb. No packs! Improve ventilation, keep the weight off the body, and low on the frame! Once you ditch the pack, you won't want it back.