Thank for answering my questions.
Are you planning to keep the rainbow shark in that tank, or moving him? Issues with behavior will not likely develop for awhile, but they are suggested for more like a 55g tank because they can be aggressive.
I asked about the angels age because if you end up with too many breeding fish in one tank, the results are not always pretty. A 30g is really the bare minimum for a breeding angel pair with any sort of tankmates, and adding a pair of rams as well might enhance aggression. However, since your fish are young, you won't know about breeding for awhile.
I suggest skipping the rams for this tank. There is just too much that can go wrong, and you have a fair bit of stock already.
If you do want to pursue it and try it (your tank), I suggest upping your water changes to more like 50% a week. Rams are also usually reported to do better at higher temps, but your neons may have an issue with that. Though, there is a chance your neons will also get eaten by your adult angels, but that depends on the angels.
In short, up to you, but I don't personally suggest rams for this tank, or the rainbow shark.