Best bet is to stop in Singapore on your way to or from Thailand, unless you want to extend your stay after your 60 days by visiting Singapore then returning to Thailand, no visa needed.
how does it get complicated? This is a sincere question. I’m planning something similar to (frequent time in Thailand but also frequent time out) and I’m curious why it gets complicated.
leave the country and start over or employ an agent. I’m also someone who loses track of time, so I put reminders in my phone for EVERYTHING. I highly recommend it. For something like this, I’m neurotic and enter multiple. Best of luck.