A few questions to be asked here.
1. Is it a good idea to have a few towers on my smurf.
2. I have a marksman, an engineer, and a serpent queen. Are those good choices?
I personally dont want any towers because it's just added unnecessary might. After all, who is gonna invade you except your main? No one if you do it right. As for your heroes they are just fine for getting the job done easily and quickly - good aoe, 2 of them are ordinary so not much might but their performance is good.
Hill Giant or Angel
Lvl 5 Archers.
This should put you in a good foundation till 2500 might. You would be able to have 4 gold vaults then and raiding is still relatively easy.
I have a sq on one of my smurfs and she's just ok. marksman, engineer, and angel are a great hero team. I have an ice queen and alchemist as well for kicks, since they really don't add too much might and are somewhat useful