the filters are positioned on the motor because you can get trash from the primer bulb or the connecting fitting from connecting and disconnecting it.
the 10 micron water separator filter is mainly for water separation but it also acts as a pre-filter so that's the one that makes it easy to access and replace. the ones on your motor can go for years trouble free.
I would only put one 10 micron fuel water separator filter of your choice and that's it. adding too many filters will restrict fuel flow and could cause issues not to mention every time you put a filter you cut the fuel line and create 2 more connections in the system that could leak at some point.
I like the marpac filter because it has a simple filter cartridge you replace and the whole filter can is transparent so you can get a good view of the fuel condition and color as well as seeing the paper element condition at a glance instead of just a little cup under the filter. it also has a water ring that floats up to indicate when water is present and you need to drain it and the replacement filter cartridgesare only $10.
look here to see more on it:
https://www.boatpartsforless.com/sho...it-with-drain/
and if you don't need the head this is the replacement filter section kit:
https://www.boatpartsforless.com/sho...FTQQ7AodcWMAyQ