woofer qts for freeair door mount

I am interested in using raw drivers and building my own crossover networks for my mid/hi's. I want to use the stock door location for the woofer and fiberglass the tweeter (home audio style) into the kickpanels. I want to do it this way as a compromise between imaging and leg room and it has worked well for me in the past.

I have been told in the past that you should look for a woofer with a Qts higher than .5 for it to work well in free air applications. However, I remember when the EliteCarAudio.com forum was still up some of the members were recommending the use of some of the Seas Prestige line woofers, which usually had a Qts of .35 or so. With a lower Qts in home audio realms I was under the impression that those are to be used for ported enclosures. Thus they would not be good for doors or kickpanels, which typically have a very limited volume of airspace.

Now my frustration comes when I look at the DIY offerings at PartsExpress or Madisound. It is rather difficult to find a mid to high end woofer with a high Qts. So I'm wondering, is this rule on the Qts for freeair apps. absolute? Or will a woofer with a Qts in the range of .3-.45 work decent for door mount?

Thanks.

Man, I wish I knew the answer to this myself. I plan on doing a system in my wife's car using 4 of these... https://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-605. I already happen to have 4 of them, their qts measures .41. Hopefully, they will work well in the doors as I am not inclined to make pods in her car. So far I have all the components for what should be a pretty good sounding system,just trying to figure out what tweeters to get before I install everything. Please let us know if you find the answer to this.