Slitherine

I have a BG of Egyptian medium archers with a BG of light chariots on their right. To the left of the archers and ahead of them is a BG of close fighters. All three BGs are in double line. I want to expand my chariots one base to either side, so I include a one base shift to the left when my archers move. This causes the archers to have their left hand file behind the close fighters, so this file interpenetrates the close fighters as it moves forward.

STE allows Egyptian close fighters and medium archers to interpenetrate.
Page 45 allows the sideways shift and doesn't list interpenetration as one of the cases where a shift is not permitted.
Bullet 5 on page 48 allows this interpenetration as long as it is perpendicular.

QUESTION 1: Can I shift first and then move straight ahead to meet the "interpenetrations must be perpendicular" requirement of bullet 5?

Assuming I can, the bases of the left hand file of archers both reach the right hand file of the close fighters but do not have enough move to pass completely through. According to page 48, bases that reach the BG being interpenetrated move all the way through. Therefore, at the end of the archers' move, the left hand file is positioned in front of the close fighters and in advance of the rest of the archers' line.

Now, according to the reforming rule on page 70, at the beginnning of my opponent's maneuver phase, the rest of my archer line is moved forward to reform with the furthest base forward, so the bulk of the archers' BG moves forward to join those who interpenetrated.

QUESTION 2: Did I do this correctly? It seemed a bit cheesy to me.

Thanks, Terry G.

Shifting can be done at any point in the move, as it is far from the enemy

I can't see anything wrong with what you did. There are far cheesier things you can do with interpenetration.