That, as you posted, is a full-time employment position. It doesn't matter what they "call" it. To you, it's a full-time job with no benefits. Do you want a full time job with no benefits? If you want a full time job, don't you think you could get one with benefits?
For me, I wouldn't even contemplate taking it. I'm a freelancer.
I would not provide an hourly rate. Instead I'd propose a contract......
If someone wants to hire me as a contractor in-house, then a contract needs to be written up where I have as much to say about our business relationship as the client and the contract can't simply be evacuated on a whim. And my fee for such a contract would be steep. It means due to the time involved, I would be unable to work for any other clients. So, a contract which essentially forces me to "put all my eggs in one basket" must provide security due to that risk - in the form of known payment for a given time frame. Nothing would be left "open ended".
Pay or play.. contract for 6 months/40hrs a week. Total contract of $XXXXX payable in weekly installments of $XXXX/24 (24 equal weekly payments, but you could do 12 bi-monthly payments). Payable in full under any circumstances. Meaning, even if they no longer want me to work.. if it's been less than 6 months, they still must pay me for the 6 month contract.