Citrus does well on irrigation as well as figs, I don't have experience with any other fruit on irrigation.

I would plant fruit trees- plums, pears, anna apple, mine are on a drip. Maybe a lime & lemon and orange. If you are going to spend money on water might as well get some thing from the cost.

Looks like 70-80 feet? East facing. Uncertain watering. Looks pretty green actually.

One, you could excavate a foot down to get irrigation out there and remove one problem. Depending upon where the top of the pipe starts.

Could also install french drains under the fence on either side per tree to carry water from back yard to future rootzone.

Two, barring that trellising grapes up against it should work. They send down deep root systems so the first year you would need to keep them watered. But the second year likely their roots would be tapped into your yard's irrigation.

May be able to grow blackberries there.

Trees? Well if the pipes don't leak (hard to believe) then trees roots should grow around them. Otherwise, I suspect your neighbor will eventually be paying to have a rooter run in those pipes periodically. I'd consider one tree centered per segment: apple on M-111, stone fruits on Nemaguard, and citrus is a more difficult call since on the superior Seville Sour Orange may be seriously problematic in the immediate future. Look for known producers in the valley and what you really like. Keep them pruned at 8-12 feet.

Here is a link that might be useful: French drains, personally just leave them hollow

I forgot pomegranate which would do well on less water. Parfianka!

Represent my tastes:
Dorsett Golden Apple/M-111
Methley Plum/Nemaguard or Myro29C (rootstock also does well here)
Santa Rosa Plum/Nemaguard or Myro29C
May Pride Peach/Nemaguard
Eva's Pride Peach/Nemaguard
Mid-Pride Peach/Nemaguard
August Pride Peach/Nemaguard
---peaches and plums are spread out about 3 weeks apart on harvest dates

Arizona Sweet or Trovita orange
Golden Nugget Mandarin (tangerine)
Midknight Valencia orange if you like orange juice after the oranges have finished in March.
If you like grapefruit I'd consider Oroblano AND Rio Red. Oroblanco for Nov-Jan./Rio Red Feb-supposedly July.
Probably avoid limes and lemons as they are more sensitive to freezes. If, however, you really like a lot of lemonade then Improved Meyer lemon is very frost hardy.
Citrus evergreen provides year round privacy. I wish I could suggest a good citrus rootstock replacement for SSO.

All trees self-fertile and very low chill hours/proven reliable in valley.

Thanks for all the suggestions! I found out that the irrigation pipes are plastic, so I don't have to worry about roots getting in them. That's why our neighbor hasn't had a problem with all of those pecan trees over his pipes.