Trees and ponds

This may be years in the coming, but if by chance liners go on sale around
my birthday - ya never know. The only place we really have, short of
totally full sun is under the canopy of several Live Oaks and Pin Oak.
1) Anyone know rules of thumb about how far away from the base you would
have to be to not disturb the 'tap roots?'.
2) What concerns are there about any trees, shrubs etc puncturing the liner.
3) This exposure would pretty much just be diffused light. Aside from
leaves and slow/limited plant growth any other negatives I'm not thinking
about?
Thanxx
Bill Brister - Austin, Texas (8b)