Since you have a source for 703, look at the Ready Acoustics bags. Seriously consider double or triple thick.
Trying to figure out the best type and location of traps is not easy, even with a SPL meter and downloaded test tones or software. It often comes down to trial and error but the corners behind the speakers are usually the best start. In some cases, diffusion works better than absortion. If it's a bass problem, below 300Hz, some healthy skepticism of manufacturer claims might help prevent wasting funds. Below 100Hz, equalization like the Rives PARC can be the only practical choice.
703 absortion/ 125, 250, 500Hz:
2" on wall: 0.17, 0.86, 1.14
with 16" air gap: 0.66, 0.95, 1.06
4" on wall: 0.84, 1.24, 1.24
6" on wall: 1.19, 1.21, 1.13
Don't know error factor for above.
As far as I know, I'm the only one around here to build DIY membrane traps, which used compressed fiberglass along with hardboard in frames.