I didn't have much luck with tenting one of mine. That's not to say it's not a good idea but it did not seem to help for me.
I have found that watering with slightly warm water has helped prompt root growth. I have also got hold of some KLN to try and prompt root growth. You can get it in the UK from...
http://www.orchidaccessories.co.uk/catalog/
(... but if that's all you want to buy from him give him a ring on the number at the bottom of the site because he charges actual postage for phone orders rather than a set value for web orders. It works out cheeper for small orders to phone.)
As for keeping the leaves from going floppy, that's difficult, especially if tenting is not working. I keep a close eye on watering, but I am careful not to overwater.
I don't know if it's a good idea, but I take mine out the pot arround once a week, and let the roots dry for a couple of hours (as well as spreading out the bark and letting that dry) then I put it back in and water again. I probably water my sick one several times a week as aposed to once a week like my other Phals, but drying out the medium and roots regularly seems to have stopped any rot.