As a potential DM, you're supposed to be a role-model... that includes using the correct kit for the job; especially in regards to exposure protection where low water temperature is a serious hazard/risk.
If you are uncomfortable in a wetsuit in those temperatures (likely), then you should recognise that using one is just a short-cut based on cost issues. A professional level diver, acting as a role-model, shouldn't take short-cuts.
Cost of a drysuit is an issue - that is understood. But then again... it's a commitment you make when you transition into being a pro-level diver.
Many inexperienced divers, who are seeking to be pros, underestimate the cost/time/effort commitment required. You will be poor... you will be cold... you will be exhausted regularly.
If that commitment deters you, then it's time to re-think and/or defer your progression to that level.