Collectible Card Game Headquarters

Is there a way to set starting life totals? The freeform Commander unlimited format is the closest I can get to playing my new format. All I need to do is have the starting life total to 20 and I am golden.

I am testing this new format I am putting together called Shrine.
-- 60 + 1 commander (any card can be your commander)
-- No color identity deck building restriction
-- Play set is 2
-- Starting life is 20

So yeah, freeform commander unlimited lets me make a deck with all of these guidelines except the correct starting life total.

Any help would be appreciated.