yep, that's right, go for front and rear angles. Aluminium isn't that stiff as many people think. You should go for a rear aluminium angle as well. Regarding the front mount, I have mixed an Alu-Angle (for cooling purposes), which is screwed on the chassis, with Carbon/glass fiber:
like that, it was quite easy to build as well. you just need a good glue (epoxy), sand the surface etc.
when you add an angle at the rear, you should have a very stiff and rugged setup, and less temperature issues.