Dear Mr Oke,

From the maximum ratings point of view it is better to use discrete power devices and build your circuit by connecting these elements as required. The power modules are normally assembled in relatively small area to save space and this is the main advantage of the modules. If you use discrete devices you can manage their thermal budget better by increasing the area of the heat sinks. We were faced with the same problem when using power MOSFETS module. We could solve this problem by using discrete MOSFET transistors having the same ratings. The disadvantage of this solution is the higher assembly cost of the discrete power devices.

However, you can better cool the module by forced air cooling ar increasing the area of the heat sink. Ultimately, you can use  cool fan to dispatch the heat from the module. You can use a little bit over sized module such that it will not get exceedingly hot.

wish you success. 

you may refer to papers on RF energy harvesting, people like yiannos manoli has published papers in this area

Active Switching Rectifier by MOSFET Employing Hall Effect Switch, a new method for reducing the heat in rectifier might be useful to you if you have extreme heat or issues with out of phase V/I .  If the heat issue is just a minor then Mr. Zekry suggestions should resolve your issues.

Interesting...