⚠Legal rights during labor? Help?⚠

So I'm wanting to know if it's possible to have a water birth for me still. The hospital I will be birthing at doesn't allow water birth if you have a BMI over 35 (same as all the hospitals and birthing centers around here). I was wondering if there is any legal way to waive that, I shouldn't have to lay on a bed because they think I wouldn't be able to get out of the damn tub (I dont want to just labor in the tub either). I was thinking maybe a legal liability waiver or something that makes my husband responsible for getting me out of the tub in an emergency instead of the midwife.

I'm going to be losing weight before my EDD (as instructed and monitored by my midwife) , healthy for the baby of course.. but I might not be able to lose enough to make it under the mark so I need a back up plan to get the birth I want for me and my child... that I should be able to have especially if no complications arise during my pregnancy.