sorry haven't read all the thread but wanted to add my experience: i had a homebirth with g&a and the baby was back to back... all went pretty well.
I'd always planned for a homebirth and when labour started and the pain got too intense i rang the midwife, they said they didn't have enough staff and i would have to come in to hospital, i refused outright and then magically a mw was available! when she arrived she took one look at me and said 'your babies back to back', this was the first i had heard she had obviously had a bit of a swim around in the last few days! i was checked and only 2cm (much to my unbelievable disappointment) - thankfully this was a good thing as it took me a few more hours to progress and mw were available to come out by the time i rang them again.
at no point did the mw suggest that i couldn't have a hb because of the position of the baby or the pain. i can't lie, the pain was crazy bad and all in my back too (i didn't feel one contraction or urge to push in the front) but it was manageable with a tens machine and breathing, i did desperately need the g&a when it arrived and also had a birth pool which i think really helped (I'm told i did relax quite a lot when i got in).
my official labour was 4.05, dd1 was born very alert and scored 9.5 on the apgar, i did tear but the mw believe this was due to how quick she decended. however she came out the right way up so must have turned at the last minute.
I'm not sure how helpful all the above is but what i would say is i wouldn't have changed anything and will defo opt for a hb in the future -had i been in hospital i would have caved in to the drugs just because they were there and i knew i didn't want that. if your sure of your decision contact the supervisor if mw in your area and fight your corner,and remember you can change your mind at any point and head in if the pain gets too bad -keep an open mind!
good luck, and enjoy!