Been there done that many times. Here's how we do it (and it seems to work ok. UF to base of tree. PVC (whole stick) from below grade to height of (min) 8'. Straps are put on loosley to allow for tree growth. Either staple or strap to tree and leave a gap to allow for growth. Hang the lights on FS boxes with enough gap to allow for growth. And the most important part is to tell the HO to call you back in max 24 months to adjust the staples/straps/boxes. When you return you simple put in new staples and pull the old or loosen the screws a bit to get them thru the next 2 yrs.
Haven't had a problem except for one HO who didn't call for 4 yrs and the staple cut the wire due to tree growth.
