If you can keep the temps right, then it'll work well. HOWEVER, if you do not have much experience with chameleons and veiled behavior especially, I woudl do this a little at a time.
Regardless, you must always have two cages as backup.
This is a really fun and interestign way to observe them more naturally. But it's a lot riskier. It's not always going to work out,a nd it poses a lot of problems. You'd have to keep a close eye on them.
I kept a trio in a 12'x'x8' cage in the spring/summer. Thep humidity was high, and the temps over 100 a few times - and they were always out in the sun. Colors like no panther could hope for!
BUT, if things are not right, if the male is not fully "socialized", he just might kill her. They need time to learn the females receptive behavior and colors. When that happenes, they won't mate unles she want sthem too. Before that, he might kill her.
it's realy neat to see real social interaction - stuff you can't see in any cage - but you have to have things right, or it's risky.