What we know from past experience is we can't have more than 2 MLS players on the field at any time if we expect to play against top level competition. The better practice is none. We played England's "B" team, which has no MLS players and our B team is basically all MLS.
England 11 1st Division.
Our Starting 11 - 3 MLS and 7 1st Division.
MLS
1-Brad Guzan;
20-Wil Trapp (capt.);
19-Jorge Villafaña;
First Division Europe
6-John Brooks,
16-Julian Green,
2-DeAndre Yedlin,
11-Tim Weah;
3-Matt Miazga,
8-Weston McKennie,
10-Christian Pulisic,
7-Bobby Wood
Someday US Soccer will figure this thing out.