Given that the eurofurence community is so successful at killing the booking servers, then it makes sense that one needs to grow, or the other needs to shrink.
Given the email writing app seemed to be running on an EF machine this year, has EF given any thought to renting a cloud computer service? I did some investigation for work last year, and I do not recall the expense being excessive, though we were looking at very different applications.
Alternatively, use the current system, but release the password elsewhere. That appeared to be the hold up this year, as what looked to be our unique ID was showing up in the URL. If we all knew that was all we needed, and the password would be published on Twitter at time X, the server you used would have been sufficient for that task.
It might also be possible to reduce the load on the server by splitting the attendees up into blocks, and assigning each block either a specific day, or a specific time on a single day. Say after staffing needs there are 1000 rooms available. Set a cut off date for room application (say one week after registration). If 1500 people have registered by that point, just split the rooms and attendees into groups. Send the information out on the 21st. Block A consists of the first 150 furs, and are given the password for the first 100 rooms, and told to contact the estrel on (say) 26th. Block B consists of the next 150, has access to the next 100 rooms, and gets to ask on the 27th, and so on. Latter groups might be slightly inconvenienced in having to wait to see if they get a room, but everyone gets a fair shot, and the server shoudl be able to cope with 150 at a time.
Finally, while I appreciate the staff have their own reasons for not wanting to get involved as booking agents, a simple electronic lottery (again, with a well publicised cut off date) could present the hotel with a list of names and contact details for furs who get first refusal.