[Opera-Linux] HOW FULLY Hide user-agent? user.js? and https?

[macintoshzoom]

1) HOW to Hide completely (blank and/or custom fake) the Opera user-agent header?

2) HOW to Hide completely the user-agent header ALSO in HTTPS browsing? 

test site: https://www.grc.com/x/ne.dll?bh0bkyd2 > browser headers >
e.g User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; X11; OpenBSD i386; en) Opera 9.27

Notes:
I dont want ANY (NOR THE 5 PRESETS FROM OPERA) user-agent headers sent, 
Opera gives only 5 choose from options. 
I,m using Opera 9.27 (linux static) on an Openbsd box, using linux emulation.
I want to set up an absolutely ANONYMOUS browsing setting (preferably easily switchable, or I will create a specific Opera profile/directory for this kind of browsing). 
I dont want to give websites/hackers any clue on my system.

TEST SITES: 
http://kluge.in-chemnitz.de/tools/browser.php
http://www.cyscape.com/showbrow.aspx?bhjs=0
http:/useragent.org
http://www.stilllistener.com/checkpoint1/env/environmentchk.pl
FOR HTTPS HEADERS (+more): https://www.grc.com/x/ne.dll?bh0bkyd2 > browser headers

It seems the tweak, if any, is using an USER.JS.
I am using privoxy with a special user-action setting that DOES THE JOB for non http browsing, ovrwriting what Opera wants to send, but not for the HTTPS as it cannot filter it, so its the Opera headers wahat it sends.

Could anyone give me the user.js code for this or any tip&trick?

Thanks