My boat does not really have much bow lift and I have to trim it to the moon to carry the bow.....how far out can I trim #4's on boxes without hurting the u-joints????

Maybe you should try spacers .. How straight is your drive shaft to begin with. Usely the joints will start letting you now when they dont like the angle. I would still try to correct the prop shaft height and work with B Blades for a good set up-- 4 blade with a different rake. If your trimming that high somethings wrong and your screwing up the design of a #4 on boxes. just my 2

I agree to start with raking first . The props can make a big difference on a surface drive .