Is the use of "be VERB-ing" acceptable in order to suggest a continuous action after "so as to", "in order to" etc.?

So as to/ in order to — are prepositional phrases and "be _ ing" are "continuous infinitives” in bare forms without 'to'.

Continuous Infinitives are one of the four variations of infinitives. Like other forms of infinitives, they too are tenseless but can set aspectual temporal relationship with main/ preceding verb to express an action in progress. They can be used in both active and passive forms(to be being played/ to be playing). Cf.

You may be joking(∅ to).

The second example of ... it may be happening... is an instance of ' bare continuous infinitive '.

All the examples are grammatically correct but it could have been better if simple infinitives were used in the first and last examples:

• If it is to happen...

• ... to rain now.