The issue you will have is that since it is a fairly flat and tall component, you need more wall strength to prevent it from bending, twisting, fluttering....
You need some sort of core like balsa or rohacell foam so that the skins are rigid and take the flight loads. I've seen a few tails done without a skin core and they were wobbly messes and seemed dangerous. This is where a vacuum system comes in. You may be able to laminate a piece of balsa down on the flat surface without vacuum but as soon as you hit a moderate curve (or worse a compound curve) your most likely going to end up with voids and gaps. Now, they do sell some stuff called core-mat which they use in boats and other heavy duty applications. I've used it in fuselages but it soaks up the epoxy and can end up heavy. I've done it without vacuum but it required a lot of micro-balloons around the edges to keep things stuck down and smooth the transition of the top layer of glass over everything.
I think the alternatives to a vacuum bagged core would be pretty heavy and not much stronger than a properly done layup.
Ya know, with aluminum mold capabilities you could make some friends real quick who'd help you with a vacuum job.
