If Bernard has a problem with metre and forced rhyming, then advising him to try a sonnet has got to be just about the worst thing to do. I would suggest he get off rhyming altogether and find his own unforced voice in free verse.
Walt Whitman was a wonderful poet who didn´t rhyme (most of the time), and yet he wrote some of the most uplifting and hymnic praises of life. The problem with most amateur poets is simply that they think it is rhyme that makes poetry, while it´s really imagery and tone.
In the case of celebrating long hair (and the beauty of the individual woman who wears it) the main thing is to come up with an original vantage point first of all and then to undermine the potential kitsch inherent in all pure praises and superlatives. A sense of humour might often help, but the difficult part then is not to let it ridicule the subject.
Here is how I once tried. Unfortunately there´s a lot of local color from Bonn, Germany, in it. The thing goes back to a wonderful long-haired student (thigh length) I used to know and desire, but never made when I was studying there a long time ago; so the poem is imagination based on the aura of summers full of romance, making some music, and dozing away hot afternoons the campus lawn of Bonn University in the 80s. And of course it´s translated from the original German:
Bonn Summer
An Azores high over the campus lawn
has also lifted the hem of the skirt
the easygoing student wears
way up into the blue of 2 p.m.
A south-part-of town night
has made her mane grow
almost down to her knees.
This desire now
to help her fix her hair -
with kisses and jazz
and her breasts in the way
and termpapers in the backs
of our minds night will fall
before this braid even reaches
the mid of her behind.
I haven´t seen the girl in ages. She works as a book illustrator, I understand, and her name is Arifé Aksoy, she must be in her mid-forties, and of course I wonder if she still keeps her hair so beautifully long and silky....