Please help with AC setup

hello, I am purchasing an A portable AC unit with 8500BTU. It will be on the the ground in a closet with a ceiling that is 8 ft tall. I will be exhausting into the ceiling into the attic. i have heard that stretching the exhaust duct this far will have two negative effects; 1)since it is not well insulated, the heat will transfer from the duct to the room and reheat it up, if i insulate it, would that cancel out this effect? and 2) the unit has difficulty exhausting straight up 8 ft high and will consume more power and burn out the unit.
Is there any way to combat this, or are there any other ideas regarding how i can improve this cooling setup? I will +Rep for good help, Thank you

Insulating it will help keep cool, I dont think that it's any more difficult to blow air up rather than out. In any case it seems like it would work better blowing straight up anyways since hot air rises.

-V

thanks man, any other ideas?