OP here. I imagine I'll just risk it and go without the contingency. I suppose I could make the earnest money on my house the same as the earnest money I'll put on a new house.. Then it will be a wash if they walk...

I think it's nearly impossible in this market. We tried and our offers were rejected for 2 different homes. One had a competing offer, so clearly we weren't going to win in that situation. The second house, however, was not under contract and had no offers in sight. The owners and their agent insisted on a 48 hour kickout clause, so we walked. We found another house a couple weeks later after we closed the sale of our first home, and we actually liked the new home much better so we never returned to the one we initially considered. That house is still on the market almost 80 days later.

Do not make a contingency. Just buy and push the closing date out an extra 30 days.

Not in our experience lately in DC. Our house is currently under contract, with all but the appraisal contingency met. We still can't seem to get anything since our financing is contingent on our house actually settling as most of our downpayment for our next place is wrapped up in the current house. We're doing a 2 week rent back after closing and feel we will have much better luck then. But even at that point we are likely going to have to pack up all our stuff and move out and into a hotel or something for a few weeks before we can close on our next place.

I bought with a home sale contingency but it was in 2012. I think the market was pretty different then. I also bought a house that had been sitting a while and needed some updates. That might be a route for you OP - if you are willing to do updates.

We are doing a rent back, but our house buying trip will be a couple of weeks prior to closing. That's what I'm worried about.