These are good questions. Let me hit them up in order.
> Are these customers who have already committed money/signed contracts? Or, would these be considered more like warm prospects?
Say a customer I have talked to on the phone or otherwise convinced to sell. Need to do a little discussion and a little work, and get them set up. I vetted them as a real customer, and they vetted me as sounding interesting. Historically at least a 75% chance to pay at this time.
> How long are they having to wait between decision and implementation? Do customers in this backlog know what kind of wait time they are facing under your current solo part-time commitment? Are they willing to wait? Or, are you losing customers to other competitors or internal solutions because of the wait time?
1-3 week range. I don't think I am losing a ton.
> What is the dollar value of your current backlog? If for example it was another $2000 in monthly revenue that is committed but at risk if you don't deliver fast - I would encourage you toward greater commitment try for a small business loan or take on your more personal sources of investment that you mention in option 3. On the other hand if the backlog is something more like $500 in monthly revenue I might suggest that you continue with #1 because your growth curve might already be slowing down.
Closer to $500 in backlog. Here is the part of the story that perhaps I did not express fully.
1) I am spending like $20 a month on google adwords. I have some very hot words. I could up it to $20 a day, and probably get 2-3x the new customer flow I do now. I do not, because my backlog would go insane. Perhaps I should do it anyway though :)
2) I have some complex customers I am turning away. They would be good for pretty good money (perhaps $500 MRR each), but I cannot yet deal with them. I know part of a young business is turning away things that are too much work, but if I scaled up and had money - I totally know I could deal with them.
So I think more than the raw backlog leaving money on the table, is #1 and #2 above leaving money on the table.