Ducted A/C Unit - Bypass Ductwork for Better Cooling??

Ductwork sealing was terrible in our Voltage. I had to retape every opening and retape the unit on the roof.

Helped a lot but it's still not very effective in the LR and totally useless at cooling the garage.

I would open up the ceiling to bypass the ducting altogether too, but there is a big valence? with light fixtures on the ceiling blocking access to the a/c.