I wouldn't recommend it. But if the seller does ship the subs together, they'll need to do it themselves and include lots of bracing. You're looking at a 40+ foot box.
This isn't about AQ, but have you contacted Jacob (from Sundown) about possibly extending pre-ordering prices for you? Explain your situation to him. He's really easy to work with.
Oh, Kranny has 2 12" level 3s on a 1500 watt Audiopipe amp, and he's really happy with them
What's the budget? I'm listing some reasonably priced subs.
For the Prime R1000, look at a Sundown SA12, DC level 4, T3 Audio T1000, or Fi Q.
For the Kicker 750, look into a Sundown SA-12, T3 Audio T600, or DC Level 3.