The obvious answer would be 6 Yorkville PSA1s subs or maybe 4 PSA2s boxes as a bare minimum but you could double or tripple that depending upon where and for what you are using the rig.
Wouldn't even look at the 2x12 sub if you need any amount of low end. might be ok for jazz AC/easy listening or conference work but if you need to replay dance or pop canned music or live rock bands the 2x15 one per pair if tops is the way to go.
In all honesty though once you go past 4 tops it might be worth looking at a real line array system as rigging 3 or4 boxes becomes involved and expensive for the gain you get if using for a portable PA
4 tops 2 dual15 subs makes an adequate system for most small jobs you can put 2 tops on a heavy speaker stand roll into the venue and have audio up in 20 mins. the Long-Mcquade stores up here in canada use them extensivly in their rental systems and they are quite idiot proof, very close to dj proof boxes.
If you like the yorkville have a look at vtcproaudio, same stuss but done with more pro cabinet finishes and better hardware as well as a real line array.