Would this Sac work just fine?

so i think i finally figured out my need for more weight for surfing in my boat. I need 1k lbs in the ski locker area, i have around 500lbs in the corner ski locker.

i had 4 people and kept moving them front to back trying to find how i can get a bigger sweet spot to surf.

i figured out that i need more back weight corner weight.

i dont wanna spend a ton, i was looking at this:

http://www.wakemakers.com/media/cata...rd_Surfsac.jpg

or i could get a coupld of these

http://www.wakemakers.com/media/cata...brick_w702.jpg

or what i would REALLY like to do is just stretch this along the back of boat (side)

http://www.wakemakers.com/media/cata...l09_sumo_v.jpg

would the sumo work or do i really need to spend the money?

I would spend the money. Maybe it is just me but I have put holes in every single cheap sac I have bought. I now have the integrated fly high kit and love it as well as a extra Fly High 350 for the front and they are damn near indestructible.