So there are several options here:
1. Find a decent MMIC within your frequency area and with HIGH P1dB. Then choose two of them to collect the gain you want (your 43 dBm/20W) and design them to be in series.
2. You could find a MMIC with HIGH gain (minimum 25 dBm) and design them in parallel with two power splitters (like a Wilkinson, so you only have 6 dBm loss (2x3 dBm)). It's a bit more complicated since the design has to be exactly the same because of the phase when you combine it again. But with this approach you get a higher total P1dB because the power is split in two.
Alternatively, if you loosen your requirements a little you could use the following MMIC. It has bad return loss, but with some matching you could make it fine. There's an example at the bottom of the datasheet:
**broken link removed**
Best of luck,
Steve