you could just stick with the basic measurements using a tape.
gaining wgt is a sure sign your growing and an accurate bf% will tell you how its being partitioned.......provided you trust your (or someones) measurements. the tape on the other hand can always tell the story. make sure you note what you measr. and exactly where (waist at navel or chest expanded @nipples, arm flexed @peak etc.). for men the 1st place fat goes is typically the waist area so that can tell you quite a bit when it comes to fat gain.
i realize your on the long, slow gain the beef without the fat plan but it wont be worth keeping the waist measr. low if you dont see any progress with the other "muscle" measurements, arms, legs, chest, calves etc.
good luck