I’ve nothing really of importance to add, but a couple of thoughts.

With the duration of their visit being about a couple of months, would it not be worth them entering on Ordinary visas instead of Tourist visas? I vaguely recall that both can now be applied for online. The difference is $5 if obtained on entry. It would provide scope for extension in a proper manner.

Secondly, if they were to approach any suitable NGOs prior to arrival, then initial introductions would be completed, possibly any basic forms and documentation could also be completed, or pre-empted, such as criminal record DBS checks, etc.
One thing about the bureaucracy is that it is slow. My experience with countries where the bureaucracy is similar is that 2 months can be a mere blink of the eye in the processing. Which would be a shame to waste a 2 month holiday waiting for something that might happen, but took another week or two of wasted time. Time that could be put to much better use than loitering on riverside, for instance.

Sorry, I didn’t intend it to mean they’ll intend to spend their time loitering on riverside. More that if you think you’re expecting a call tomorrow, or maybe one more day, you simply may not venture very far. Which can easily turn into an entire week, by which time you start to look back and say

what if…?