Precision has always been proud of their units, so it would not surprise me that they sold it for $20K. Rule of thumb is to double manufacturing costs to cover expenses and margin, so with a sell of $20K, we ASSume the build cost would be around $10K. For a US built unit, that is probably in the ball park.
You have a 4" X 18" column, with a capacity of about 226 in3 and your pot is an 8" X12", or about 603 in3, or about 502 in3 with a couple of inches of clearance for boiling. That means you have room for about two column volumes per run.
Two volumes is not the end of the world, as the first two do most of the work, but the large fat column is also less efficient than a skinnier one, so I would consider replacing the column with a longer one of smaller diameter.
If you look at the column top cap design, the material at the outside edges of the top of the 4" column isn't directly impinged on by the LPG. For instance, a 2" X 48" or a 3" X 24" for a three-volume flood. The 2" would hold about 1.3 lbs, and the 3" about 1.4 lbs. Your current 4" column will hold about 1.9 lbs, depending on moisture content and preparation.
My thoughts are that it would be a shame to use your Precision unit to open blast. From a safety, cost, and environmental standpoint, there is little comparison.
When I got into cannabis extraction about 2007, folks were open blasting using PVC pipe and there were regular home, motel, and vehicle explosions. We were also using lighter butane because the gas companies wouldn't sell to the newly legal medical cannabis industry, as it was federally verboten.
We discovered high concentrations of "Mystery Oil" in lighter butane and needed a way to remove it before using the butane for extraction. Today using reagent grades of LPG, we still encounter this issue, though at greatly reduced levels.
Besides total cost and Mystery Oil, consider all the impact on Mother Earth by the exploration, extraction, and processing the LPG before we use it our process, so just using it one time and venting it to atmosphere as smog seems like a cop out.
As far as subsequent processing, it depends on what you want to end up with, but 10 days on a hot plate before vacuum oven processing, will most likely produce a decarboxylated high CBN product. What were you hoping to end up with?