Chris,
If you use Sig dope, then you should use Sig thinner too.
Duplicolor paint cans have an adjustable nozzle that shoots a knife edge pattern and an adjustable tip to spray vertical or horizontal, or in between. That makes it a lot easier than any other rattlecan brand to get good even coverage with fewer passes, so even the enamel might go on lighter than others. You can sweep faster and a little closer. It also dries extremely fast.
I prime first with NAPA DC-540. (DC=Dupicolor). But I had bad luck with the Duplicolor branded primer, it got hard as hell and impossible to sand, unlike the soft 540. You can sand it back down within an hour of applying it, but it won't fill deeper grain and dings. I also used the acrylic Laquer rather than enamel, but it's not fuelproof. So for your needs, I say go with the fuel resistant enamel and try to keep it light. Remember if you get small fingernail and bump & ding impressions in the balsa, a drop of water wiped on with a fingertip or damp paper towel will make them swell up and disappear for good.
This is just one more opinion to rattle around in your head. Try to cherry pick the answers and be consistent in the choices you line up to go forward with the job.My Twister came out very light, but I had M'koted wings. The last time I flew it(still experimenting with weight and balance), it was 41.7 oz with an aluminum spinner(like the one I showed you), fp.40, Eric tongue muffler, and metal tank. My new wing will have it back in action pretty soon. For my training needs, I'm sticking with M'kote wings for now.
Rusty