OK Josh, here's what I'm thinking in regards to you coffin cooling issues. If the pictures on this thread still reflect your current setup, meaning nothing has been changed or added, then I have a few suggestions to prevent foaming issues (unless your foaming is due to overcarbing, etc., which is a seperate issue). The first is insulation.....if your insulation is still what is shown in the pics, then it's not nearly enough. I like the way you used expanding insulation around the PVC ports within the wood columns, but the coffin itself needs a lot more. The styrofoam insualtion sheets that you used are very low in R-value and it appears as though you used just one layer except for the corners (again, unless you have added more since the pics.).
I would replace the front piece of wood on your coffin and raise the level of the taps a couple of inches. I would then caulk the hell out of every wood joint in the corners. Then I would systematically fill the entire coffin cavity with closed cell polystyrine insualtion panels creating a channel for the air to flow up to the shanks and back down to the exhaust port. Of course you have to be creative in making an insulation access panel to get to your shanks. Raising the shanks a couple of insulations will ensure that there is adequate R-value in the floor of the coffin (cold air sinks). Coffins are much more efficient when there is a small column of airflow up into the coffin, across the shanks and back down to the exhaust port. The smaller the volume of space needed to keep cool, the better. You cannot insulate these things enough. In my experience, insulating the entire cavity of the coffin except for the intake port, the shank channel, and the exhaust port, is by far the most efficient. Also, you need to add weather stripping to your wood access panel on the back to prevent air leakage out. Again, a tight fitting insulation panel for access to the shanks is need beyond the wood access panel. I have pics if this doesn't make sense.
This moves onto my next point. How exactly is your fan set up? I read on NocturnalEMT's thread that you are using a computer fan. Are you using one or two? I'm not sure if a computer fan is going to move enough air volume or not, but I think that you have a better chance of success if you have one fan blowing into the coffin (intake) to bring cold air up out of the freezer and into the coffin and another to exhaust the warmed air back out of the coffin and back down into the freezer (exhaust). I used Inductor fans that are designed for HVAC systems as duct boosters. They move a ton of air and are not terribly expensive. Computer fans may work if you have an intake, an exhaust, and a smaller column of space to circulate through, and of course, you are well insulated in the coffin.
If you get a chance, post a few more pics. of your current setup, where your fan (or fans) is positioned, your back access panel to the coffin, etc. and we can go from there. I have reinsulated and tweeked my coffin a few different times and now have it working great. I have a TSS2 controller, so the fans for the coffin are controlled independent of the freezer compressor. They run off of a seperate temp. probe inside of my coffin. My coffin fans turn on for less than a minute, a couple of times per hour, which they are designed to handle. My compressor only runs for a few minutes every few hours. You mentioned that your compressor turns on for 10 minutes about once per hour. That's a little too frequent IMHO. I have some ideas for that as well, if you care to here them.
Your setup will be fine and functioning much better with a few tweeks! I'm happy to send you pics. and give you as much advice as I can, but I know how frustrating foaming issues can be and am happy to help you out if I can. Let me know.....Good luck!