The easiest place to tap into the fluid is through the drainplug.
easiest not always the smartest....
think about these points....
1. What is the purpose with the reservoir? stock back up volume of oil, provide expansion space for oil, allow ENOUGH time for oil to release air, cool down, and sediment water and particles.
2. What is the purpose with the drain plug? drain above sediments, take oil test samples
3. How does "unwanted objects" or contaminants, get into the oil?? coming from the system via return line, through the fill cap when filling oil, through the air vent, condense water from air in tank
4. How can we prevent "unwanted objects" or contaminants from getting to the oil reservoir?? return filter, fill cap strainer, air vent filter....
If you do not prevent the cause of "head ace", you will always have "head ace". Above "treatments" prevent head ace, a suction strainer is like Aspirin, only has a purpose when you already have head ace.
Unless the inside of your tank is the source of "unwanted objects" or contaminants, you do not need a strainer. Just prevent "unwanted, objects" or contaminants get to the tank.
A lot of posted hydraulic problems this cold winter, has been related clogged suction strainers, due to high oil viscosity in combination with water contamination.
But I am unsure how to install a simple strainer here.
put it in the fill cap hole...
It would have to be very small because space is very limited.
That makes the strainer idea even further away from reality...
And the simpler the better.
cant be simpler than that
BTW, adding another pump into a current system....make sure you have a reservoir sized for the additional oil volumes you put in circulation....see point 1 above......