With all the stipulations you have, you are basically OUT OF LUCK. There is no way to make a working backup without the use of a mod chip. Also you stated you didn't want to have to swap. There are only a handfull of MODCHIPS that can do that. Rec. is to say SCREW the warranty and get a Messiah mod chip... Have it installed by someone who has done it before...... SORRY for the bad news but thats LIFE......