I suspect that removing the water before precipitating DMT salt from the naptha will give me meaningful quality results.

To do this my first idea is to use a dean Stark Trap. As I do not have any of that apparatus, before I do anything I will be bogged down in building one and frankly that is not the only project cluttering up my bench.

Does anyone have any experience with this or thoughts on the subject?

That sounds like a lot of trouble to go to.

I've got tons of the things and haven't used them in years... They're typically used to drive a condensation reaction forwards by co-distilling water out with benzene or toluene.

Are you a glass blower? Otherwise, how do you propose to build your Dean Stark apparatus?

Why not just dry the naphtha with MgSO4? Or even anhydrous Na2CO3?

If I do a smaller extraction, a separatory funnel is used to remove the whole water layer.

For "full scale" extraction where my small sep. funnel is not large enough, I use reagent bottle and pull with pipette into and intermediate tall beaker or the sep. funnel.

The residual water is then removed by decanting or drained.

If small droplets make it to the crystallization dish, they are easily visible and can be removed by soaking into a paper towel.

I never thought about using drying agent for the pull - interesting!

SWIM used MgSO4 to dry out some xylene that have som acetone in it and it grabbed some moisture from air... extraction went good...

I am not sure if MgSO4 is a suitable drying agent for naphtha (although may work for xylene).

Magnesium sulfate is not listed as drying agent for pentane, heptane nor hexane: this table.

For xylene, they recommend calcium chloride, sodium or molecular sieves.

Well, we're talking about a solution of tertiary amine in hydrocarbon so even solid NaOH would do the job. It's not like we're doing finicky organometallic reactions, magnesium sulfate really will suffice.