The answer to the OP = Take it.

Be a mug for a while but when the economy is better let them be the mug and move on.

😆

Haven't read the thread but..
I interview for jobs regulalrly and will tend to prefer people in work over those not. Sometimes it's obvious in the cv that the current job is a retrograde step and if someone says they took the job to get back into work, but are looking to getting their career back on track – good thing.
I'm also not averse to hiring someone who is likely to move on for the reason that I get a higher skill set than I'm paying for, but prefer people are honest and keep me up to sped on what's going on.

Take the job but if they know you're taking a lot less than you were on before, and is fair for your experience, they should imagine you're likely to leave when things get better. Maybe worth discussing what prospects there are but whatever – I'd take the job! More experience and less time unemployed will only look good in the future. When you change jobs in the future it won't matter that you're paid less now – you'll be able to negotiate whatever's fair.