We use Wedbush Futures. This is possible. I would need to learn more directly. My email and phone number is below.
You should check whether pre-trade block allocation or post-trade is possible. Also - don´t know whether this is still common practice with US FCM´s - whether average price allocation is possible. The UK futures brokers allow only "First in First Out (FIFO)" allocation. And don´t use FCM´s who claim to have electronic access brokers who claim to have DMA to Asian derivatives exchanges and then the whole order routing process is being executed through their "desk" (oh boy!).... Oh, and ask Wedbush whether they will grant you intra-day margins (preferably of course only 20% of initial exchange margin that is)
RE Nighthawk comments - Post Trade allocation (Preset), yes Average Price, no to 20%. We focus on CME, CFE, ICE, and less so on foreign exchanges.
I used them in the late 90s and early 2000s with POA and Block Account. You'll probably pay around .15 cents more per round turn than AMP but you'll still have the low day trade margins you are looking for. https://www.gffbrokers.com/