First, one doesn't exactly "maintain" mulch - you just let it be to do its thing. The majority of groundcovers tend to be rather shallowly roots plants, ofter rooting from their stems as they grow, so planting directly into a thick mulch is unlikely to be very successful.

Underplanting the pine with something like hostas will fill up the area quickly and you won't see a lot of mulch but it is best if you scrape away the mulch before you dig the planting hole, then rake it back to not quite the base of the plant (leave a little 'breathing' room!). Hostas rapidly expand to a significant size, they come in a skazillion different leaf colors and bloom (some with considerable fragrance) and they are quite drought tolerant when established and immensely suitable for a shady, under tree area.

But only if deer are not a problem. If they are, forget the hostas.