Your right on the money on the reasons of crown reduction. I would think a combination of crown raising and reduction is the best you can offer in this situation if they dont want to remove the tree. From the knowledge I have of it the problem lies in limit the reduction and raising to a level that is not going to risk the health of the tree. This may be something that would need to be done over a matter of a couple of seasons to limit the stress on the tree. I guess the good part is it would give you repeat business for the next year.
1. Crown Thinning
Crown thinning, primarily for hardwoods, is the selective removal of branches to increase light penetration and air movement throughout the crown of a tree. The intent is to maintain or develop a tree's structure and form. To avoid unnecessary stress and prevent excessive production of epicormic sprouts, no more than one-quarter of the living crown should be removed at a time. If it is necessary to remove more, it should be done over successive years.
2. Crown Raising (Fig. 4)
Crown raising is the practice of removing branches from the bottom of the crown of a tree to provide clearance for pedestrians, vehicles, buildings, lines of site, or to develop a clear stem for timber production. Also, removing lower branches on white pines can prevent blister rust. For street trees the minimum clearance is often specified by municipal ordinance. After pruning, the ratio of the living crown to total tree height should be at least two-thirds (e.g., a 12 m tree should have living branches on at least the upper 8 m).
On young trees "temporary" branches may be retained along the stem to encourage taper and protect trees from vandalism and sun scald. Less vigorous shoots should be selected as temporary branches and should be about 10 to 15 cm apart along the stem. They should be pruned annually to slow their growth and should be removed eventually.
