I have a cinder block home in Zone 5b (WA state) that needs new windows now but I plan to add exterior insulation and siding in the next 2-3 years. I will most likely insulate with the Legalett Thermalwall PH system. What would be the best way to install the windows now and ensure that I can still add the insulation later? My concern is not being able to insulate the block window frame if I just install the windows directly into the block.