60cm would be better. I have a hawthorn hedge on my Northwest/Southeast boundary and it's doing very well but there is no fence either side. I don't see why it wouldn't work for you as long as you prepare the soil well before planting. Dig it to a depth of between 1.5 and 2 spades, remove stones, rubbish, weeds and then put the soil back with plenty of added garden composta nd well rotted manure to improve its structure and nutrients.
You can buy whips - short, single stems - of hawthorn in autumn which is also the best time to plant. Soak the roots in a bucket of cool water for an hour and then plant at 9 inch intervals if you're doing just one row which will be enough for your purposes. For a thicker hedge you can plant them in two zig zagged rows at 9 to 12 inches. Trim the stems to 9 inches high and water well. They will spend autumn and winter growing new roots which will then provide the energy for new stems in spring.
Mine grew 6' in their first year. You'll need to trim them back to about 3 or 4 feet heigh the first autumn after planting to encourage them to bush out and thicken up and so provide more flowers, berries and shelter for birds and insects. You can keep them trimmed to 6' thereafter. How wide you keep it is up to you.