To my knowledge the PCB can be used if there are no problems with reflected power. The amplifiers I know, up to X-band, have isolators at their output, to prevent load reflectivity problem.
In cell base stations filtering is quite a problem, so to reduce insertion loss and get the high Q needed for reject band, cooled filters are used. PCB in principle is a lossy material, usable only over short distances. In my company we do use microstrip by Rogers up to 110 GHz, but as short as possible. Waveguides are much better, low loss, etc.
I did not make a PCB filter at ~2 GHz; I prefer cavity and coaxial filters with which a low insertion loss as well as a good rejection is easy to achieve. For Wilkinson couplers, PCB is used but I do not know how it behaves under a high power and some load mismatch. I would simply try it and see.