Mike,
I can give you my experience, but I have not ever tried this over dope. First of all, any heat shrink covering over an open bay is very difficult due to the elasticity of the base covering. But over a sheeted or solid surface it's works well. Monokote requires high heat to stick and if you are going to use it, I recommend using Windex (with ammonia) or Trim Solvent. Low heat coverings (including Ultracoat) can be heated to the surface with good results. I have done this over surfaces painted with Rustoleum, Nelson's, and Duplicolor with good results. Note, the smaller the trim piece the easier it is to work. Trapped air bubbles are always a problem so I cut larger pieces into several small pieces. Edges blend together well and are not noticeable. I suggest you try practice pieces first. This will tell you whether dope will work, but also it will allow you to get the iron temp exactly right. Iron temp is very critical!
Paul