Blowing out a white background without flash

I want to save my Speedlights to light up the model so I don't want to waste them blowing out a white background. So my idea is to get 2 of those fluorescent high power bulbs with reflective umbrellas on both sides of the white muslin.

Has anyone done this and been able to shoot at f8 or above and if so, what wattage bulb will cut the mustard?

For the amount of power you'll need you probably wont save much over buying a couple of vivitar 285 flashes.

If you do go the mixed lighting route put the speedlights on the background and the hotlights on the subject, that'll buy you a few stops worth of shutter speed back. Oh, and watch your white balance.

don't forget by going the flourscent route, I won't need triggers either and a blow out is a blow out......0 information on the cmos so whitebalance isn't an issue. I will just need to make sure i have enough distance from the muslin.

maybe.
but, you might run into shutter speed issues.
your muslins will need two stops more than your main to "blow out "
and since you need a particular f stop for the subject, that leaves only power and shutter speed to control the backdrop light. and I'm not sure your fluorescents have that sort of power unless you are using a large lens opening or a high ISO.

Unfortunately it's just not practical and it's going to force you to work at longer shutter speeds, wider apertures and perhaps higher ISO's than desirable.

I don't think it's a good idea.