Presumably you are planting it for the fruit harvest. Which means you will have to get right up to it, step on fallen fruits in season wherever you plant it.

Yes for fruit but I’m always walking around the front yard for other things so I think I would track more inside if it was in the front.

Locally written article on the tree - I wouldn't bank on it staying a mere 15' tall (without pruning*):

Hybrid mulberries are best. Crossing the White and Red species results in a tree with the most desirable attributes of both. It grows splendidly in our climate, is hardy to extreme cold if need be; delicious berries are borne over an unusually long period (late June through late September); and the tree is exceptionally vigorous.

https://arthurleej.com/a-mulberry.html

*Speaking of which when I have been there it seemed like just about all of the various kinds of trees in the Raintree orchard were heavily pruned. If nothing else being repeatedly headed back by the gathering of scion wood

This sums up everything I have read so far. So do u think planting it 25-30 ft away from septic field would be ok if the tree only gets to 15 ft tall?

15 ft tall if pruned then ^^

Expect roots to reach farther than top. And that's farther than full sized top, that has not been curbed by pruning.

I will measure a few other possible locations this afternoon.

Do u know if they would do OK in part shade?

Measured and I might be better off with a s anklet tree. black beauty mulberry might work instead.

All mulberries have water seeking roots, mine are twice as far as the canopy diameter.