I hope you don't mind, but I did a little research, based on your prevalent symptoms, to see if there were any other avenues to explore. I am sure you have done this exhaustively, but I just wanted to see if there was anything you could safely try that might make life a little easier for you
I have not tried the flowmax and I don't think I will mainly because of all the side effects, especially on top of all the other crap I take....
The baclophen probably won't actually make the bladder muscle and the sphincter work in unison, but it will make the bladder muscle less hyperreflexic (make it relax more) which will reduce the pressure in the bladder caused by excess muscle contraction, which may make the dyssynergy less extreme and the sphincter more able to relax too, at the right time. If you have some intermittent incontinence caused by the high pressure in your bladder, this might also be helped. I am no expert though, this is just based on my own experience of the drug, which I initially took for a completely different reason.
I have found that while I still battle to get going and have to push a bit, once I start, the flow is much stronger and better - not so much "starts" and "stops" and dribbles!. Baclophen can worsen fatigue, and it gives me a headache, but no vertigo.
I can only imagine how debilitating that must be for you - I have only had vertigo a couple of times for just a few days, and it is really awful. An added benefit of baclophen is that it may help you with the vertigo - I did some research on vertigo, and attach the url for you to read (you have probably seen it before), and towards the bottom, it mentions baclophen as a possiblity in treating vertigo.
There are also listed many other possible treatments for vertigo for you to discuss with your doctor. BTW, I had serious problems with anticholinergics - they worsened my urinary retention, and made it almost impossible to pee - this may not happen to you, but just be on the lookout for it if you decide to take any - it reverses in a few hours of stopping the drug, so no big deal.
Whilst I fully understand your not wanting to mess with the trial, I think that maybe you can get some measure of relief from your symptoms while you wait, so that you can still get some enjoyment from your life
Maybe if you find something to help, but it makes you more tired, you could ask your employer (just for a couple of months) if you could just work a 5 or 6 hour day (no lunch break) or do a coupleof hours from home via your PC - if it's for a short duration, most employers would consider it, and hopefully, once the Tovaxin gets working, you can up your hours again. Maybe work 8-2 then go home and nap, then work from home from 4-6, or something?
But life is hard right now for you, and I would love it if something could be done to improve it. Is the Sativex spray avaiable in the US? It is not available where I live, but I believe you can get it in Canada - and that might help you too.
Any way, I hope you don't mind me butting in, and I hope you get some relief soon.