as i’m just getting started with the adapters as well as your super cool app, i sure didn’t go the easiest way. tcp does work, but with the exact drawbacks you explained. i was going to set the esp up as an udp-bridge in the next step, so thanks a lot for the fw you linked.
the sparkfun-item you linked is the exact level converter i used. i combined it with a 5-to-3.3V stepdown reg giving reference for the hv and lv sides, rx/tx are simply connected to the signal pads on each side. it does work alright as well, but the 5V-ready modules sure are much more convenient.
so thanks a lot and keep going! if you need betatesters i’d sure be pleased!