Upon further research the cloaks in musketeers would be casaques (or cassocks or mandilions from some sources). They show up relitively rarely in art though there’s one in Hendrick Pot’s a merry company at a table for example, which is from 1630. 

Perhaps more relivently for my purposes reconstructing history have a pattern – not entirely sure I need one if I can size it correctly by myself but someone else might find it useful if they find this post