re: polyurethane application

The triple thick is new to me ,I really don’t understand that approach . When finishing with oil base ,if you want a thick finish you usually let the first cure sand it back and recoat. I have been spraying finish for 40 years so that’s my choice as far as applying stain and finish. I think you made a good choice by going to a water born product. I really suggest using the finishing techniques Charles Neil uses. He has a great book on the subject.
http://charlesneilwoodworking.3dcartstores.com/Charles-Neil-Finishing-Simply-Put-Chemistry-Degree-Not-Required_p_238.html