I like a 20 Long for a build for them since they are mostly bottom dwellers. 4 should but just fine in a 20 long.

I siphon my drainage area with a hose but you could drill and build in a drain hole if your ok with drilling glass.
Magnolia leave can be boiled then dried in an over at about 200 degree but you have to watch them carefully so they don't bburn up.
I get mine from josh's frogs for pretty short money. I use the live oak and sea grape leaves since the live oak is smaller and the sea grape has some cool colors.


As for ventilation, Pick up the matching glass split canopy top and instead of using the plastic extention where a filter system would go, make a screen like the ones used for home windows.

Its actually simple and I bet you could even give the measurements to a Lowes employee and they would cut it for you.
When cutting the material take into consideration the corners.

Here is a link to making the screen: How to Make a Window Screen: 10 steps (with pictures) - wikiHow

Here is an example from the front of one of my verticals. your would be just made to be placed on top.