Hi I'm hoping that someone can help me!

I'm making some prototype flat parts. At the moment the surface finish isn't relevant as i need to finish strength testing the parts to finalise the lay up.
At the moment I'm using 5mm 3DCORE in the part and I'm wet laying up all the carbon and core in one go and then putting under vacuum. 

When I come to make the actual part I will resin infuse it so I get a better surface finish and it's what the core is designed for.  I'm trying to figure out a way to get the same surface on the back as on the front. The only thing I can think of is to have a 2 part closed mould where I lay up everything into the mould wet and then put the two halves together and put in an envelope vacuum bag? but I can't see a way of doing that using resin infusion?

Any help or opinions greatly appreciated !
I've attached a picture of one of the test parts still in the mould for reference. ( I will also be making a new mould before I start infusing)