get away with 1/2 mdf for small subs?

I just got a pair of ed 7kv2's. I have a small rx7 hatch and am trying to take the least amount of space up possible. With the help of the box calculator, 3/4" mdf only gives me .66 cu ft air space for the pair. If I use 1/2" with a brace in the middle as it is a long skinny box I get over .7 which is the recommended sealed space. With a brace and all other good stuff taken into consideration, am I looking at any loss with these small subs? I would use 3/4" for anything larger but these things are small and it does seem a bit overkill to spend the extra space and money for the thicker mdf. Someone with small sub experience would be nice. thanks in advance for the help. Looking forward to posting up pics of my first ever full install on my project car.

The major problem using 1/2 inch is getting it fastened together. With 3/4 you can put in a dry wall screw or a brad nail. No problems. To use screw or brad nails you with 1/2 inch you would  need something like say a 1 x 1 or at least another piece of 1/2 inch about 1 inch wide strip to border your joint to shoot into. By adding in that you just cut into the rrom being saved. Not to mention more cuts andmore time to put together. So IMO a waste of time. Just get the 3/4 it will save time and aggrevation. Its only a few dollars more and the space saved is going 1/2 inch would be minimal. 

It would be acceptable if built well and braced well......and if its not going to see alot of power.