Hello,
The boom truck may need to enlarge a bit. If compare with the picture when the 1/72 scale gound crew stand next to the master.
http://www.macross2.net/m3/sdfmacross/boomlifttruck.htm
There are no official specification/length and size. May be a good looking size should be overweight, by comparing with nowsaday working vehicles. Scaling IMAI 1/100 Macross Factory may not produce good result.
Ichijo