Tramadol is a weak opiate type drug to begin with. On top of the sub would be even more pointless. The small amount of narcotic effect that would take place I assume would then be reversed the next day when you take your AM dose of bupe.
Though not likely to cause actual precipitated WD's taken in the manner you describe having a small amount of another opiate on your receptors can be uncomfortable when you take suboxone the same day or next day.
As for the SNRI properties they are minimal at low dosages and in high doses you are at a greater risk of a seizure. If you want to experiment with a drug that acts as a serotonin releasing agent do some research and you could find a number of safer alternatives.