For the Tern, I think I would go with the luggage truss. It is, I think, designed to help cope with cables, but it also elevates the bag. If you look at a Brompton 16" bike, the block has a larger clearance to the fender than the block of the Tern. You can place a headlight between the bag and the fender. On my 20" with a Brompton block, I mount the headlight to the handlebars.