I have the same tank, and have sought out more range on most bikes I've had. In order to know how much is in the tank I plan to ride to empty, mark the tank level, then pour in my 1-gallon Rotax and mark it again, then proceed to nearby gas station and mark each gallon thereafter. That way you have the option of minimizing your fuel load before riding technical sections.
Had a KLR650 with a 7 gallon IMS tank and marked it the same way. Heading home from Montana I pulled into Denio Junction for gas only to find out it was out of order. Barely made it to Adel, Oregon, but knew it would be close based on fuel level. That's the reason I like the translucent gas tanks.
Sure, I prefer the looks of the 3 gallon IMS with the stock side covers, but I don't like my trips to be planned around gas stops.