Big picture: when your rack comes, assess the strength of that bracket. A 10-gram reflector, no problem... but a 70-gram taillight might eventually fatigue it and break it. A DiNotte 300R, at around 160 grams and costing $200 if you lose it, deserves a hardcore ultra-strong bracket.

As an alternative, consider removing the Axiom's reflector bracket, and bolt a dowel to the underside of the rack using that hole. Now you can use any seatpost-style light bracket on the dowel. I can recommend the Cygolite Hotshot if you'll be using a fender to protect it from tire spray (the charging port faces downward), it's got higher straight-back intensity than the 300R at a fraction of the weight and expense. And it will easily dominate the SF Turbo, Radbot 1000 or Mars 4 too.