We make mead with rose petals every year (rhodamel). We collect rose petals all summer and freeze them. We always add raspberries. We put the raspberries and petals in a mesh bag in primary, pouring very hot, but not boiling, water mixed with honey on it before closing the lid on the fermenter, then yeast is pitched in the morning. We use a lot for the rhodamel and while it is perfumy in aroma, you get used to it after a few sips and it actually has a lot of complexity. For a beer definitely don't put it in the boil. I will try this some day myself, and by the way I think a saison is a good choice. I would use about two cups of petals for 5 gallons in the same method you use dry hoppingp and freeze some for bottling. Taste and smell at bottling, if the taste and aroma is not enough make a tea with a couple more cups of petals, don't put them in while the water is boiling, you want it as hot as you can short of boiling and cover as soon as you put the petals in. ( you could use your priming solution) then strain and stir in. Be sure to collect petals that are aromatic, not all roses are very aromatic. Ragosas work well, we grow some for this purpose. Also, be very sure the roses you use are not sprayed. I have been thinking that a successful rose beer will have a distinct rose aroma upon pouring then fade back a bit.