Checking some options for tail light for long rides (more than 100 km and 5 hr), I found this XOSS XR PRO. After some tests, works fine and the battery last for a long time, but seems it's not made for AERO seat tube. A well designed rubber could solve this easily.
Others AERO solutions are too much expensive (more than $ 50 USD), then I decide to go ahead with this XOSS XR PRO and make some smart

solution to install the tail light support.
If you asking me to install under the seat with the other support (included), the answer is NO WAY! I need to carry my tools.