Leaving a PPR for 6 months

My sister bought her home 18 months ago, and now it looks like she is leaving the country for 6 months for a job. It's an opportunity she cant pass up, so she's taking the chance, her employers here are holding her job open for her.
This is her only property, and to be honest, she's not 100% sure if the job is going to work out, so possibly may be back a lot sooner than the 6 months.
We are trying to work out what is the best thing to do with her house, I was hoping to get advice from some of you experts

Has she any other options than these:
1.Rents it all out straight away, but there would be a clawback of the stampduty and she would have to pay a few thousand. (She would have no problem if she was leaving for a long space of time, but with the uncertainty of the situation, if she had to come back it would be such a huge loss of money for her, she really cant afford it)
2.Takes a 6 month break from her mortgage and leaves the house vacant (she is worried about this, in case the bank think she's renting it out on the sly and trying to evade paying tax)
3. Is it possible to let out a room in the house under the rent a room scheme, and she could stay in the house when she is home visiting (about once a month) ?

Sorry this post is so long, its just such a unique situtation. I feel so sorry for her, we are really unsure of the taxes involved and she is absolutely terrified of doing the wrong thing and getting fined for tax evading. She's like my dad that way. Any advice would be appreciated, thanks a million.

Go for (2) or (3).

I'm sure if she explains the situation to the bank, they will understand.

It's not really a unique situation, there are quite a few threads that address this issue.

I may be wrong but I believe that in such a situation a family member can live rent free in the property on her behalf and it will legitimately remain her PPR during that time. In that case it may even be possible to avail of the rent a room scheme. Although getting a tenant for a 6 month or shorter period may be tricky? Maybe somebody else can comment more authoritatively on this? The Revenue summary guides to Stamp Duty mention the "on his behalf" issue but don't clarify it in detail. I presume the final arbiter on this would be the legislation (TCAs) or independent, professional advice (which I think your sister should seek regardless).

If the house is left vacant for the period then alternative home insurance cover will probably be required since most home insurance policies only cover vacancy periods of c. 30 days.

Thank you most sincerely for that information, (especially about the insurance) it definately pointed us in the right direction. I just want to help her any way I can, I really appreciate it.