Cutting trunk

Almost completed cutting the hole in the trunk for the rear battery box. There's something satisfying about watching the sparks fly when you cut metal. The conversion instructions I'm following are not great and the folks I got the kit from are not returning calls. Still I think it's ok. I'm a bit worried that I'm weakening a supporting cross-member. If I get this thing running I wonder how long before I have confidence it's going to work.