Well, first off, you really need a serious input module with a proper envelope follower. That'll allow you to take foley-type audio and run it thru the machine, deriving both audio and envelope CVs from the signal. Given that this is something you'll likely want to use with both a proper mic and/or line inputs, have a look at Cwejman's AP-1. This also contains some compression and basic eq, plus line and mic (with phantom power) inputs. At $685, yeah, it's expensive for a Eurorack module, but the price is actually pretty comparable to pro-grade mic preamps. As for the Ears and the Detect...nah, probably won't work like you think. Ears is a contact mic built into a Eurorack module and usually works more like a controller, and the Detect is a bit too simplistic to give you the envelope control that manipulating foley really needs, to say nothing of tinkering with highly-amplified microsound-type sources.
Clouds: not available anymore, unless you get lucky or unless you can get a third-party version of it. Otherwise, it's a good choice, but you might want something more delay-like as well for sound looping/manipulation. Check out Make Noise's Phonogene or Morphagene, as well as possibly 4ms's Dual Looping Delay.
Filters are really lacking here, and that'll be a problem for making major timbral alterations. In this case, you'll want two different kinds: 1) a pretty complex, crosspatchable VCF (or several in one module) and 2) something more fixed, such as a filterbank, to use like a complex equalizer for basic spectral alterations. Doepfer is a good source for both; their A-128 filterbank can be gotten with a separate break-out expander to directly tap the individual passbands, and the A-127 Multitype Morphing Filter (along with its companion A-144 Morphing Controller) in conjunction with the MATHS will allow you to do a lot of complex, unexplainable sonic transformations. As for the LPG...mm...it's OK for instrument-type work, but sound design has a lot to do with complicated timbral alterations, and so more complex filtering would probably work better for you.
The lack of VCAs here will be a problem, as you don't have either a way to control amplitude of audio signals or control signals via a modulation source, and both are really important in any form of synthesis environment. Consider several, and you might look at Intellijel's Quad VCA as a possibility, since you have quite a bit of flexibility of VCA behavior in those plus the module also is capable of functioning as a 4-1 mixer.
Overall, the biggest problem here is one of scale. If you're trying to set up a sound design for SFX/foley device, that's one thing...but an instrument-type synth is somewhat different from that. It IS possible to do both, by having your sound manipulation/alteration paths in the same cab as an instrument-type path...but you might need a bigger cab. Also, go have a closer look at a classic SFX synth: the ARP 2600, which Ben Burtt made ample use of for sound design for the first 'Star Wars' movies. While there's certainly been some improvements in the gear since that synth's day, the basic design principles in that synthesizer are sufficiently open-ended for both SFX design AND musical work, and it's a good point of reference to work from. Doing a bit of research into Suzanne Ciani's work in the 1970s in sound logo work (using a custom Buchla system) might prove useful as well.