Use a camera..

I use a mirror a lot, it's good for some things but as you said it doesn´t reflect exactly what the spectators will see.
It has an extra promblem, you get used to performing for yourself, I don't know how to express this propperly but I realized that when performing for real audiences, my positions and attitudes were very close, like if performing to myself.
Some magicians gave me advice and told me that it was dou to excesive mirror usage

You could always buy a couple of security camera and place them in different parts of the room and watch it live from all different angles on the TV (this might cost a bit though). Also, if it is a poor quality system then it will be delayed.

P.S. I do not have this but I am consider getting it in the future.

Xaethia

Since the key to misdirection (for me) is to train your eye to look where you wish the audience to look, a mirror can disrupt your natural moves and conditioning. I use mirros only when learning a sleight so that I cna check finger position, coverage and naturalness of hand and body position -- then use the vieo camera or mentor for a realistic appraisal. In short you "cannot watch yourself" and be natural.