There was an excellent article on how to handle this in Free Flight Digest. November 2004, I think. Bob Stalick was the author. I use this system and it works quite well.
There is also a force multiplier lever setup shown in the same issue which allows one to use a Badge timer on larger models which need strong stab hold down force but a relatively slow running timer.
See if you can round up an issue. If not, let me know via email and I will mail you a copy. 😀