Personally I wouldn't want the additional pressure of having to dash out to buy a bed for the baby immediately after arriving.
What if the flight is delayed and you arrive very late at night? You'll all be tired and the last thing you'll feel like doing is dashing out to buy a cot.

Why not hire a standard cot for the older child? That way it will be there at the villa when you arrive.
No hassle - both babies can go straight to bed.

Your villa owner will be able to organise this for you.

In fact it would be worth asking the owner if they can help with this - as they may have a neighbour who would have a spare cot you could borrow. Certainly, our villa neighbours are such good friends of ours that we would help each other out in this way.