Bodgeitandscarper I went looking for myself for Elaine Cater, and she is still around, and guess what you can buy her books/patterns via PDF's so that is good. She actually has a garter carriage one specifically for electronic machines so that might be useful. What sort of width are you looking for? do you want your sweater or cardigan to go straight up from the hem, and are you doing a rib for a hem? Another thought about getting extra width, is to have the seam coming from the middle of the shoulder as in princess line shaping, or a little further over at the edge of the actual shoulder and instead of an underarm seam knit that part wider therefore you will have the same seam on both back and front coming from the shoulder and no underarm seam - that can be a flattering line as well.
Whilst I haven't knitted for quite some time, I used to use what was called an industrial two by two rib, and this was a much nicer rib than a normal two by two rib, and I am racking my brain to think of exactly how it was done. I know I certainly cannot get at the bench of my cabinet where this info will be, but I can at the moment get at my knitting bookshelf, and perhaps later today I will have a look amongst my many books up there. I know I have the Brother Ribber book, and there were lots of useful ideas in there, although at the time I did not have a brother machine, however some time ago now I had the opportunity of buying a brother ribber for my punchcard Brother, so that is handy. I will also look out the books I mentioned recently by Pam Turbett, as that might be a nice alternative for you to just knit long lengths of knitting, and then treat as fabric and cut and sew this on your sewing machine and overlocker, then you should definitely be able to get the width you want.
I know you said you were not to keen on the purl side of tuck stitch, have you looked at the knit side of tuck stitch? This can be unexepectedly full of surprises, giving hints and definition of something that is not just plain stocking stitch, and then again you would possibly get the width as tuck stitch spreads widthwise.
I also mentioned some of the other stitches that the machines can do, and in particular mentioned a lace stitch, then of course after I had posted this I remembered yet another stitch that was peculiar to the Brother machines, and that is fine lace - I have never tried this, but from memory I had seen some lovely garments knitted using this technique.
I do hope you are enjoying your current bout of knitting, this can be so rewarding, so have fun.