I have a tummy sleeper here, but she hated tummy time in A time. Someone suggested to me to put a rolled up towel under her underarms/chest to give her more height, with some toys where she can reach. It worked a treat, she lasted much longer on tummy time quite soon. Now we don't need the towel, she often does a good 1/2 hr of tummy time. Not always, depends on mood, but often.
HTH