Hi,
Yes, some product custom field could be useful for your needs.
In the backend, your client can select the size or colors and in the front-end, you can display them like you want, by overriding the product page.
You can no display the custom field in the "show_block_custom_main" (filtering on $fieldname) and display them in another place in the page (or with a different look).
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.