As others suggest attach to turning blocks out on the spreader underside rather than on the mast. I do that. That makes the opening wider. It puts no strain on the spreader.
I also use a Stack Pack which I think you call a bag. I wouldn't be without it. The lazy jacks attach to the Stack Pack sides which have long boom length fibreglass battens inside a slot in the fabric
. There are about 4 holes through the batten and fabric
with small SS shackles for the lines to tie onto. The lines can be very light. Mine are 4 mm.
Additionally I use a downhaul on the main sail. It's 4 mm spectra and ties through the uppermost sail slide. Then a slightly slack loop and a sail hank clips onto the halyard
eye above it just to retain the halyard
in the unlikely event of the shackle undoing. ( yes it did happen prior to that and was my fault) . Don't tie onto the headboard as then it falls over and jams when pulling down. The downhaul needs to be coiled so it will run out when you raise the sail. Then it's secured by a small cleat so it doesn't blow back when sailing.
My downhaul runs back to the cockpit
as does the main halyard. Now I can pull my main up and down without leaving the cockpit. If it is breezy I'll sometimes slacken off one side of the jacks before raising the sail. Then I let the wind
blow the sail slightly over that side so the sail doesn't flap around and catch a batten.
It all makes sail handling easy.