I have to add 3/4 oz of weight to the right wingtip of my .46-size WM P-51. I have to figure out how to CLEANLY hack into the fiberglass wingtip, add the weight, then CLEANLY patch it up. Any ideas?

My temporary solution is to stick on 3/4 oz of lead to the bottom of the right wingtip on the CG. I've read that these things have a tendency to fall off in flight, so I sealed it with clear monocote (photo attached).

Is this an acceptable? So far it has stuck on for 2 tanks on the ground, including taxi practice and practice take-off runs. The plane has not flown yet. Will the altered airflow at the wingtip have any adverse effects?

Thanks,
Juice