The 1100 and 100 RS fairings are interchangeable and use pretty much all the same mounting hardware. IThe K100 in my avatar has an 1100 lower fairing. All I needed was the left and right lowers, belly pan, and the knee padding. All I needed for bracketry was a brace under the engine for the rear of the belly pan. I made one myself out of a strip of 1/8" stainless sheet. Took me a couple evenings to make all the measurements and bend it up.
Some of the bracketry may be different between the LT and RS fairings. An evening copying part numbers from the Max BMW fiches should give you a pretty good idea of what you have already and what you will need. These bikes share a lot of fairing parts across the different models. A lot of what you need is on eBay and if you aren't in too much of a hurry, you can cop some decent deals. Some of the parts you need have been there a long time and the sellers may be eager to deal.