Filter dilemma

Miata

I have a Roth tank installed outside. Boiler is in basement.  Have had no problems so far this winter, but wanted an osv. The three major ones say to have filter first, then osv. I currently have a General canister filter next to burner. Read that outside tank oil performs better if warmer so decided to have first filter where line enters house, the osv, then line continues to original filter. I believe with two filters oil will have a greater chance to warm up. Purchased a Westfield spin on filter and read in the directions that the osv should come first to protect filter if tank is above boiler. So, filter first, then osv, or osv, then filter. Thanks for suggestions