Thanks for your advice.You have better reach with the 70-200 and 400. They will both work fine with the 1.4 tc you can crop or do dx with the 70-200 to get between 200 and 400.
The 400 is super sharp and between tc's and cropping.dx you can handle up to 800. If you don't use a tc you can get the benefit of the wider apertures. Very often using these lenses in tandem you don't need to use the tc.
I use the 135 plena with plant and flower photography. as well.
If you got the 500 pf I would stick with the 300. They work well together. As a bonus get the Plena and have it handle the shorter ranges. You can crop quite a lot with that beast.
You will not see the plena discounted for a very long time the lens is too popular. I did find an interest free two year deal with Nikon direct so I am paying 100 a month for two years. I am giving up my Peloton bike for it so it is not affecting my cash flow.
135 Plena is very amazing, no doubt. For portraits and close photography, with super nice bokeh, I would keep in my wish list. If I can use this for travel purpose, I can try from lensrental. It is $100 for 5 days, manageable. In Yellowstone, I can shoot Bison as they are close, as well geysers. For Costa Rica animals, it may run short. Light is low in dens forest and 135mm can be fast enough for that kind of situations.