Mark, yes, of course my Grandad French Polished, he was cabinet making! But If it's good enough for a cabinet maker and it's good enough for Riva and Freebody's, it's certainly good enough for anyone else!
E-mail me and I'll send you a picture of one of my Riva models which are made/veneered in steamed pear, which looks like mahogany in scale if you stain the finish. I would use cellulose sanding sealer….a few coats, then rub down, then stain with hand mixed spirit based stains, rubbed on with a fid, then spar varnish with a broad sable brush, till a glass like finish results. The spar varnish puts a hint of that golden tint to the pear that is part of new mahogany. These methods I always used when making miniature furniture for dolls' house collectors.
Of course, a teak deck has very little colour anyway, so you probably need no stain at all!
Cheers,
Martin