I had to look up exactly what "subjunctive" means to understand what you're saying.
"May she be strong...." is pretty much exactly what I was going for.

BTW, I know this can be a tricky question when dealing with Irish translations, but what is the exact translation of Go raibh?
And does this mean that the literal translation of Go raibh maith agat is "May goodness be at you"?

I rarely use grammar terms
We use the subjunctive for praying and wishing something to happen.
Like in English you'd say: If I were you....
were - is the subjunctive.

Yes, "may you have goodness" would be a direct translation.

Other people may be able to explain it better, or correct what I've said. As everybody knows I'm not good at grammar explanations.

Thanks all for the input and help.

I rarely used grammar terms either, which is why I had to look up what subjunctive meant.

So, in conclusion, I think I'll go with:

Go raibh sí láidir
Go raibh sí saor
Beannachtaí uirthi i gcónaí
Bíodh sé amhlaidh

I know that 3rd line should technically be Go raibh beannachtaí uirthí i gcónaí, but do y'all think it's within the limit of poetic license to leave Go raibh off of that line?

Yes. "Go raibh" is often left out in such phrases.
e.g. the common phrase "Bail ó Dhia ort" is a shortened form of "Go raibh bail ó Dhia ort"

Your explanation is perfect.

I could only add:
A very literal translation of Go raibh maith agat is "That be goodness at you".
"Go" is obviously the conjunction "that" used as a "subjunctive particle" (or better "optative particle").
No literal form of "may" is needed in Irish.