Suffix '-ageous' (as in 'advantageous') [closed]

The Longman Pronunc. Dict. includes the suffix '-ageous' (beside both -age and -ous), stating that this suffix may impose rhythmic stress on the preceding stem, as in advantageous /ˌædvənˈteɪdʒəs/.

Does such a suffix really exist, or rather Longman is in the wrong here?

Compare the entry for -age (or -eous):

In most words -age is /ɪdʒ/ (perˈcentage), although some recent French borrowings are pronounced with /ɑːʒ/, stressed in American English and sometimes in British English (ˌentouˈrage). Some words have two or more competing variants (garage), and there are exceptions (outrage /ˈaʊtreɪdʒ/).

Longman is correct, at least as I pronounce the words.

ad-VAN-tage -> Ad-van-TA-geous

In 'advantage', the primary stess is on the second syllable. In 'advantageous', primary stress moves to the third syllable and a secondary stress placed on the first. It has a nice little rhythm.