If using an urn with a concealed element you may need to give the element a scrub a couple of times during the boil as i found out making tonys roggen. It caked up pretty fast and cut out. Had a consistency of engine oil almost, i loved it but others didnt like the mouthfeel.
From several years ago: 70% rye malt, 25% Vienna and 5% Caramalt. Can't remember the hopping (something German to moderate bitterness), but fairly sure the yeast was Wyeast 1275 Thames Valley. Unfortunately parts of my blog disappeared. Did this in a mash tun with a false bottom and a grain bag, so BIAB should present no problems. This was for home. Very drinkable, the keg lasted about a fortnight. Should do another.
I'm still deciding if it is going to be a roggenbier or a APA with rye (about 30%) based on the responses here. I'm sort of leaning towards a roggenbier for simplicity's sake (as in flavour profile).
@seamad will heed the advice about it catching on the bottom.
Thanks for the link. Doing some research roggenbiers are apparently half barley, some wheat, some rye. Looks like I'll need to do a protein rest, mash out and sparge. Either way I'm pretty much preparing for a long and messy day.