Temporary loan for one week - transactional funding appropriate?

I'm anticipating on making a cash offer on a small office building in my area, which means that I'll need to submit a proof of funds letter with my offer. The cash will partly come from the sale of another property that I'm closing on in one week. So I'm in a situation where I'd like to get this property into contract ASAP, but can't write my own POF for another week. I know that transactional lending is usually used for a double-close during a wholesaling deal, but I'm wondering if they'll do something similar for this situation. I essentially need a bridge loan or a temporary POF to hold me over for one week. Any ideas?