I have never done a backglass before, i think it being printed onto the glass would be the best thing, what is the soap and water thing?
Printing onto glass will cost you some $$$'s.. you will still have to add a transluscent white layer and then the blockout layer.. its quite a bit of work and any BG has 3 layers. Once youve done the artwork for the front you will need to make a file for the back also so you have the hidden numbers, GAME OVER etc.. the front is only half a BG. BUT!!! you are very handy with photoshop by the looks of it.. wish i was, i use Corel and it lacks some of the features of PS.
Mitch.. keep making your artwork files.. youre doing a bloody great job mate. I have a few BGs im making D.Riders is one of them, but process is the same... let me post and then decide if you want to go to the extra expense of print onto glass.
Gav