I haven't been posting long so please excuse the late post on the subject!
On the subject of heating monofiliment knots, don't. 16LB test should be enough to hang most anything, 20LB is just plane hard to break. I've fished all my life, 47yrs. One of the absolute golden rules of knot tying is don't heat monofil. Many still do so. Don't! Applying enough heat to melt the knot enough to freeze it in place will degrade the strength of the line at the knot by 80%. If you're using 50 or 80LB line it's probably not going to fail. But with lesser tests you're really taking chances. I've tied knots in everything from 2LB to 100LB mono. Your biggest problem is probably going to be knot slipage. Make sure you're making the knot correctly and pull it down snug. Slippage is usually the result of either a missed step or failure to pull the knot down snug. I know all about knot slippage, lost two one hundred pound class tuna (and two $10 trolling heads), back to back hookups, to slippage
Get a book on fishing knots and practice!!!! Also, if your models are going to hang in direct sunlight, get a brand of line that's UV resistent, then change the line twice a year. UV breaks down monfil
Weigh the plane!!! I just got a 32nd scale P-47, The thing's big but it doesn't weigh much more than a couple of pounds. Six or eight pound will hold it fine. Large test line is harder to tie knots with, six to twelve pound is real easy to work with. I lost those tuna because I had no experience with knots in 50LB test. Weigh you plane and double it, I'll bet you'll never need more than 15LB.
For those who plan on hanging their 1/16 King Tigers I would suggest you look into learning how to twist piano wire
David