Yamaha DTXpress/DTXplorer/DTXtreme

Hello All, I had an idea that might be fantastic, but i dont want to 
go into it without running it by the pros :)  OK, I've had the 
DTXpress III since mid March but havent used it much outside of 
practice and fooling around.  Last week I tried it in the setting of 
a band rehearsal with my group and it was FANTASTIC to play on while 
working on vocals.  Unfortunately as soon as we tried to jam with it, 
we found that it just doesn't have the ability to make the intricate 
sounds i'm looking for in a jam kit.  I was kind of disappointed, but 
listen to this idea:

I want to try to mute my acoustic drum kit but use the mutes as 
homemade triggers.  That way i can use my DTXpress in context of the 
band for vocal work, and then just pick them off when we start 
working it loud and jamming.  Also, I can keep my mutes at the 
rehearsal space, and my DTXpress kit at home and just move the module 
itself.

My thoughts were to buy basic drum mutes, for example from 
http://www.percussiveinnovations.com/deluxe_drum_mutes.htm or 
something like that, and just throw a piezo on the back of each one. 
I expect dead spots as the design seems kinda flawed but I'd like 
them as nice as they can get.    

Is it necessary to have a piece of something hard on the back?  I'm 
not overly concerned with stick response when working on VOX.  Also, 
am I completely insane, missing something hugely important?  If so 
please let me know, $ is tight for me now but I'd really like to get 
this working.  Thanks alot guys, a million thanks already,

-Matt