Don't overlook your ability to be the market maker on these contracts - with one lots. You can even move the market - and change the charts, with one lots, for the cost of a single commission. (Have you ever sold to yourself?) With the difference between initial and maintenance, you can free up equity for other trades by temporarily moving the lightly traded market. The automatic calculation in TWS doesn't care who made the last trade, just the price of the last trade. It also doesn't care if the bid\offer is yours in that calc. Disclaimer: Consult your legal counsel regarding legalities concerning "market manipulation" vs. "protecting your position."
In an email I received from the head of customer service, I was told that the software used in calculating contract value only had problems in the YI and YG, in that the front month is not usually traded. He mentioned that March/Feb (yi/yg) should have been used as front month a couple weeks ago and that also the software should have recognized the extreme difference between the front and next month and thrown out any "outlier" quotes. The only problem I see is not recognizing that in the case of YI and YG, the front month stops being the active contract far sooner than other electronic issues, and I believe they are working to fix this problem pertaining the metals. In regards to selling to oneself, I'm sure that is done all the time in the thinly traded equities and is no big secret. It would have been no big deal to just throw in a 1 contract bid on the December to smooth out the price, but IB does not allow any trades to be entered for that month this close to expiration.
Any physical commodity with electronic contract that has a pit traded counterpart is potentially going to have this problem because the pit decides when rollover is. Sometimes rollover can take a couple of days to fully happen. In index futures, the rollover is done on a set day.
mBear: It's quite acceptable to make a market in an illiquid instrument, but you cross way over the line when you talk about trading with yourself for the purpose of deceiving other participants or risk-management systems. It's not hard to spot when you are used to trading a particular illiquid instrument and two new players show up and a print appears out of nowhere. Reasonably current risk-management systems (like IB's) don't give much weight to prints anyway, preferring to use bid/ask, models, and quotes of related contracts instead. No legals opinion required - manipulate markets and you should and will get caught.