Water tight and dust sealing

I have camper shell that I bought from Alibaba. There is a little water coming in from the front left and very little (sometimes none) from the front right. I would say a little more water coming from the tailgate section on both end side of the camper during heavy rain.

If you have a similar camper shell. How did you dust sealed and water sealed the camper?

 

Typically can seal with foam strips, or if you're never removing the cap, foam spray. the are never 100% waterproof though.. water goes where it fits.