If you continue with tautening dope, you just stand a chance of inducing warps as the dope continues to shrink, and as the model ages, having the covering split easily. It just keeps shrinking over time. Doing the build ups, and covering applications and initial clear build up with tautening dope is what gets you the tight appearance, so you are on track there. Randalphs may just need to be thinned a bit more to spray when you shoot it, or even if brushing and will need to be plasticized to negate the shrinking properties. Dave Brown Flex-All is available for that purpose and works well. If you decide to proceed with SIG colors, they are all based on SIG Lite Coat, which is non-tautening dope. Both Butyrate and Nitrate come in tautening and non-tautening varieties. It would still be well worth your time to search out posts by Bill Byles on the subject as he gives a great dissertation on how to finish with dope on several occasions. Bill ought to just write something up and have Sparky pin it to the top of this section.
Type at you later,
Dan McEntee