Canadians can currently enter visa free for 60 days at a time. With breaks of 5 weeks or more in the middle of stays is less likely to draw attention. Always good to have proof of your work abroad (ie a work visa or similar), proof of where you will stay and proof on an onwards flight out of Thailand.
Either get an extension of stay before leaving and a re-entry permit. Or, if you have legal Thai family, get a 60 day extension of stay based on family, and a re-entry permit.