Non-skid bathtub coating...Suggestions?

My new girlfriend has multiple sclerosis. We’ve been shacked up for a few months now. She has told me that she would be more able to get in and out of the bathtub on her own if it were less slippery. While bathtime is fun for both of us, I am looking for a coating or treatment that would make the tub safer for her. I need something that will work in a fibreglass-type tub. We have tried the stickers and strips and they suck. Any suggestions are welcome. Thank you SDMB buddies, I know someone will know what will work effectively and be inexpensive, too.

It may help if you tell us why stickers and strips suck. Have you tried a tub mat?