As far as tank design with low volume, take a look in Summit or Jegs at 'dry sump' oil tanks. The good ones are designed with a cone shaped bottom with suction being pulled there and the return fitting is welded into the side of the tank to promote the fluid to swirl. That swirl makes the bubbles say to the outside while the good oil without bubbles is pulled out of the center bottom. Most hydraulic tanks are larger capacity. you may also want to slap in a filter somewhere. I had a small tank, pump, motor, winch set up and it pulled great once...then stopped. Couldn't figure it out until I pulled the hydraulic motor apart. The pump must've picked up a piece of weld slag or something that came loose or was unseen the pump pushed it through but the motor tolerances are too tight to absorb something like that and still work well. Hint, hint...