Swamp,
Since each model is shipped at 80% for the specific draw length ordered, you cannot get 28.75 and 80% let-off with your bow. You are already at 80% baseline.....a move to the long side will give you some more draw length but as pdq 5oh stated you will be over rotating the cam way too much and let-off/ valley will become sloppy.
You can't have both........
What you have available to you on your specific module is a downward bit of movement in draw length and let-off. As you go to the short side "S" , you will be decreasing draw length and valley by whatever physical distance you move the peg because in effect you are underrotating the cam a bit. Move it 1/8" and you will decrease draw length by 1/8".

The let-off settings are pretty precise......only a 1/2 line, or full line makes a big difference. I don't have a post setting chart for your bow to give you the setting for 65% and your module. The comfort level for each bow is pretty much limited to the area BETWEEN the 80% and 65% setting.....at least for me. Anything else is too extreme in either direction and not recommended.
Yes they are supposed to have 1/2" mods for 2004 but I have yet to see a set.
Your best bet is the 1/2" module to give you a 28.5 at 80% setting, They will be able to give you the exact post setting you when you have the module.......question is if the mods have been cut yet?
The .5 module for 28" will be as close as you can get via module and post setting to what you desire.