For me it is less of a size issue and more that the height of the g604 puts my wrist at a weird angle. I find the triathlon much more comfortable. The g604 was in stock when I needed it and I dont have much bad to say about it other than it is too tall for me, and the software is a royal pain to save your settings to the on board memory.
For keyboard consider ordering a switch sampler and see what you like. If I reccomend a keyboard its gonna be something hotswappable with tactile switches because that is my preference. Maybe look at the gmmk or the kemove shadow. Both should be available for under 100. Dont end up liking the switches you chose, you can change them later pretty inexpensively.
For a numpad I am using a wireless mechanical numpad. It isnt anything special, but it works well, and can be placed out of the way when not in use.
Really it is going to come down to trying a few things out. Some will work for you and others wont.