All of those upgrades could be handled by the UA-5. Unfortunately, it is not easy to stealth (although others have done it).
The problem is, the more you upgrade, the bigger the equipment gets, the harder it is to stealth. If you are going to stealth, here's what I would recommend: stick with the equipment that you have, but run your battery box off of 2 9V batteries (giving you 18V). It's the cheap easy way to get more SPL out of your mics. I did it for a Dream Theater concert and it worked great.