I don't really have any advice for you, but I feel for your situation - it's exactly why my band split. We were offered a 5-6 week support slot on a tour, mostly in France and four of the five of us were prepared to chuck our jobs if the extended leave couldn't be negotiated with our respective employers. The guitarist was the fly in the ointment which was particularly annoying as he was self employed so could have easily picked up where he left off if we came back with nothing but a bit of good/bad experience. Even worse all of his "self-employed" work came from the same guy, who was not only a good friend of his, but our No.1 fan. He owned the building where we rehearsed and wouldn't even take money for rent or power because he wanted us to give us all the help he could to try and take it to the next level. No way would he have had a problem with it and he even told him so when he became aware of the situation. He had a mortgage and such, but so did I and the drummer. The pay would have been much the same as we earned anyway (actually more in my case) so the only real risk was how long it would take to get a job again when we came back if that was required. He was the only one who didn't have that problem, but the only one that wouldn't go. Go figure ? Cold feet or under the thumb from Mrs Guitarist ? Who knows ? My money was on the Mrs. Replacement wasn't an option as there wasn't time and he also owned a lot of the stage gear which he said we couldn't use when a stand-in was suggested. Even more galling for me was that the final band meeting where we tried one last time to persuade him, failed and so decided that there was no point in continuing if we weren't going to take the opportunities that came our way was the day I made the final monthly payment of 18 on the keyboard that I couldn't really afford and it was finally mine. Great ! Nice keyboard - no band !
From my experience, it's hard to see that things will be the same between you later on if they don't come on board. Hope you find some kind of resolution. Good Luck !