I like your thinking but suspect that other factors will prove more important. Those other factors would include spacing of the trees, rootstock, pruning, and thinning. The idea being to have an open canopy and moderate crop load that will reduce disease and promote regular cropping of high quality fruit.

As you suggest I'd give the late ripening cultivars more sun.

You logic seems sound but unless you are growing varieties that ripen very late then it probably won't matter too much, just that your harvest might be a week or two later than it would be otherwise. I think the other importance of sun is that more sun equals heavier crop. When I was a kid I would find apple trees growing in completely overgrown old farmyards and those trees would receive at best some filtered sun since they were heavily shaded by taller trees around them. They still produced apples, just very few. But I think if you are getting at least 6 hours of sun a day then that will be ample for a full crop.

I've tried to order my trees by vigor (not that they've reached full size yet). To the south, I put the shorter trees (mini-dwarf), then B9, then G16/11. Within each group, I did my best to sort by the cultivar's vigor (William's Pride being to the north of Goldrush, as WP grows faster/taller)). This helps keep the shorter trees from being shaded by the taller trees. Of course, slope of the land is also a factor.

If there are other tall trees, it seems reasonable to think about the sun distribution over the season. One thing to keep in mind is when the other trees drop their leaves. My neighbors have a few large trees (Ash I think) whose leaves fall early enough that it could help my late season apples.

The problem with canopy shade is it may get worse every year- trees that aren't growing are dying. Not to be the tider of ill fortune, but the amount of sun does have a bearing on fruit quality as well as quantity. Full flavor comes from full brix which comes from full sun- at least in my Z6. The best fruit I harvest is generally from sites with dawn to dusk sun even if there are also other factors in play.

Plums have done well for me in relatively shady sites if you can beat back black knot (fungal disease is generally much worse on trees without eastern sun). Apples vary from variety to variety in how shade affects quality. It is true that latest ripening varieties seem to benefit from the earlier defoliation of forest type trees where the canopy opens up just as they begin to ripen.

It is important how much sun fruit gets right up to ripening with exposure in the last couple of weeks before harvest being the most important, IME, and I've long used your approach for positioning (and choosing) varieties.

If the OP lives in California the sun is enough, but around here I am with HM, full sun or nothing. It's not just the crops and the eating quality, it's the fungal diseases. Peaches are even worse.

For that type of sun here, I would plant mulberry, blackberry, raspberry, hazelnut, pawpaw, haskap, juneberry, currant and grapes. Perhaps even hardy kiwi. Select varieties that do well one zone lower than yours. There are a number of other fruiting shrubs, I have no experience with them, such as cornus mas, which are reputed to withstand partial sun.

I didn't mean to suggest "full sun or nothing" and 6.5 hours of direct sun should be sufficient to produce very nice fruit but the issue of eastern (morning) sun is important for stone fruit if you want to keep fungicide sprays down. Black knot is not even controllable with spray. I'm speaking for the humid regions here.

I am concerned that your exposure will shrink every year as surrounding trees extend their reach.