oldilliani1, reading your post it seems to me that the thing you really struggle with is the rubber dam and it looks like you just wished your dentist to perform a root canal treatment in the way you had it years ago. It must be pretty frustrating even trying to cope with it and not being able to.
You mentioned not being able to follow through with "their procedure" ("them" being several endodontists). Please correct me if I'm wrong, but it sounds like you haven't been given much of control during the treatment.
Looking at the options you have, you could get the tooth out and get an implant as you mentioned (which sounds pretty expensive and very invasive), getting sedation - there are many kinds of them (you said you were afraid about your sleep apnea and Gordon replied that this won't be a problem, but you haven't mentioned whether that reassurance is enough for you to give that route a go), asking the dentist to allow you to hold the saliva suction that you could use to keep your mouth dry, as letsconnect suggested.
My thought was - and reading about your strong aversion towards rubber dam, I'm a bit hesitant to mention it not to upset you, but will give it a go - that maybe becoming a chance to get used to the rubber dam may help you get a sense of control. I was wondering whether you were offered a stop signal, breaks or anything else to feel comfortable.
Many people struggle with the rubber dam (and I needed few visits to being able to even cope with having it on) and it really feels like a barrier, but in theory, you should be able to close your mouth a bit with it which could make the swallowing easier. I know the feeling of resistance that the thing causes and as I tried to close I gave up, but on the other hand I didn't try too much and I trust my dentist saying it is possible. Also, your dentist should be able to remove it pretty quickly whenever you feel the need to and a nervous patient friendly dentist will be willing to do so. Sitting up and taking a break whenever you feel uncomfortable lying, should be possible too. You mentioned a spacer that also makes it difficult for you to swallow. I was wondering what you mean by that - is that the block you bite on to relax your jaw? Because if so, then this part is to help you if you like so and it should be fine to refuse to take it.
All those things would require a dentist that is willing to help you and who you can communicate with clearly. It may take a bit of research and contact with practices to find someone, but given how much this is bothering you, it may be worth of trying. If you are open to it, of course. If you are not, then feel free to forget everything I said
Last but not least, however annoying rubber dam is, it enhances the success rate of your root canal treatment and decreases the chances of losing the tooth because of bacteria getting in during the procedure. That's one of the reason why in the most countries, rubber dam is obligatory and the dentist has to use it.
This is super long, but I felt the urge to asdress this point too, mostly because I had been a rubber dam hater myself for a long time.
Hope you find a way to get the root canal treatment, in whatever way it will be.
