the set up should make life easier, rather than harder
to be fair, if launching and recovering were easier we'd all be out on the water more often!
do you mean the roller cradle inverts? i.e. there's too much weight, from the rollers, on the top and it swings round, so it's upside down? (Owners/users of Warrior boats will be aware of this problem!)
the rear rollers should usually be a little lower (this is a broad generalisation - all hulls vary!) than the front rollers. This means the boat will roll off when launching, utilising gravity and then winch on in a fairly straight manner, utilising brawn, but not 'over' the rear rollers - there shouldn't be much effort involved in the first instance of drawing the boat on to the trailer.