A bivy is good for stealth camping but for about the same weight you can get a Tarptent that sets up on trekking poles. Of course, that is not very stealth.

I think you need to borrow a bivy and use it for a week's trip. Some people simply never adjust to a bivy. I am a small person and find my bivy about right sized by the time I put all gear inside. I wonder how a big person does in a bivy.

I use an OR basic bivy which has a bug net. I have done many 10-day trips in it. Works fine if not a lot of rain.

I often but not always take a sheet of Tyvak for a ground cloth. Not needed, but does protect the bottom a bit- the bivy should last a bit longer and it keeps the bivy clean. If worried about a broken zipper, just have a knife with you inside. Always have a head lamp inside - stay calm and most often the zipper is just snagged on material and you can get it unstuck. I have never had any problem with my bivy zipper. In a big storm you will want to zip it all the way up.

A small tarp to cover your head is handy to have. It does not have to cover the whole bivy. A poncho works too. Set these up on your trekking poles. By the way, will you have trekking poles?

If it is hot and humid, a bivy can be very uncomfortable if there are bugs that require you to keep it zipped up.