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As far as I know, if the working frequency is under the series resonant frequency of the component, then there is no problem. Unfortunately, not all the manufacturers offers informations about SRF. For example, take a look at Kemet spice, , this manufacturer offers nice graphs with impedance vs freq. for their caps. I use regular 0603 and 0402 at 2,5GHz with no problems.
Can you make your own capacitors? One type is thin filaments in an interdigital structure. I have also seen parallel plates, air dielectric, types soldered perpendicular to the PC foil. This is really a short open circuited transmission lines.