Maybe you could try to use the "RF Design and Analysis" toolbox by Jackson Harvey. You can download it at https://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=261&objectType=file. If I remeber correctly the power amplifier is not included, but there are elements to simulate distortion, noise and other RF characteristics.
However I'm afraid it's limited to linear power amplifier.
There is also the RF toolbox sell by Matlab, but I don't know what's inside.
Hope it helps