Winger Howlett and versatile teenager Toeava could join Auckland team-mates Saimone Taumoepeau and Kurtis Haiu in a strong Marist line-up in a Premier Division clash at Pakuranga United's Bell Park on Saturday.
However, Auckland coach Pat Lam has not allowed injury-prone scrum-half Steve Devine to start ahead of the NPC champions' pre-season tour of Fiji and Samoa.
Marist coach Peter Kempson told The New Zealand Herald: "Wayne Smith and Graham Henry have encouraged them to play club rugby if they want to.
"All three are very club orientated and they've fitted in very easily."
Toeava played against Argentina in Buenos Aires last Sunday but Howlett missed the win over Los Pumas.
In Wellington, fellow All Black quartet Ma'a Nonu, Chris Masoe, Piri Weepu and Neemia Tialata will turn out for their club sides.
The All Black selectors willingness to allow certain Tri-Nations squad members to play club rugby may give a clue to the identity of Henry's preferred starting XV to take on Australia in Christchurch next week.