Converting battle to field and vice versa just involves exporting the model as a .3DS using biturn and then reimporting it like you would any other model.
Including resizing and adjusting for animations, it may take you 30 minutes tops.
If Timu doesn't care, I can release the field model version... but unless I'm mistaken he and Millenia were planning to revamp both Barret's model and texture.
Alternatively, it may even be possible to simply rename the individual part files into their corresponding field .p files, though I've never tried. But then I don't think lighting will effect them either