Hello,
There is no need to lie. Going multihomed is reason enough to request and obtain a /24 from one of your two providers, despite the fact that your network size only requires a /28. I have performed this exercise for companies of your size many times over, and trust me, any major network provider will give you a /24 if you are switching over to BGP and getting a second connection.
The effect of imposing a /24 or greater limit on BGP routes is that providers need to be more sensative to the needs of companies who, when considering network size alone, can't justify a /24. Thus, going multi-homed is enough of a qualifier by it self to obtain a /24 from an upstream ISP.
-James
