IMHO I would invest in a reputable TPMS before replacing the tires. But that's me. When it comes to Westlake, there's 2 frame of mind. I have the TireMinder I10 and I visually inspect the tires at the beginning of every tow day and often when we are stopped for lunch. The CRE3000 will improve the tt suspension, As for sway, that might be because you Don't have enough tongue weight.
Treat your tires like this, work on weight distribution and you will surely age them out. Try not to get caught up in the weeds over this China tire hysteria there’s always more to the story. After you get a good TV weight and then a combination weight of TV & TT do the math and figure out the actual weight coming to bare on each TV axel and trailer tandem . Use the attached Weight to Inflation guide to determine the proper PSI (add about 10%) for your rig. There is absolutely no reason to go straight to Max. Cold inflation before understanding the weight being transported. Not many 15” tire options above load range E and that may overkill for your rig.
https://tirepressure.com/
As for the CRE 3000, highly recommend this as your second suspension upgrade. I ran the Dexter EZ ride for three years and recently changed to the CRE 3000, it was like putting shocks on the axels.
Reach out to Performance Braking @
https://performancetrailerbraking.com/
Met these folks at a Rally, they will be able to make sure you get the right parts.
The third recommended suspension item would be a single X brace between your center spring hanger where the CRE 3000 will bolt up, got to remove this bolt during installation anyway.