Use a 3 way valve at the return T of a looped system. That way you can switch to a normal return when you change filters to purge the air.
Then switch it back to loop when finished.
Have fun.

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'70 F100 shortbed
'82 Diesel Westy
'83 Euro 300TD
Curtlo Viper
Yeti ARC
Surly long haul trucker