An update on how things are progressing:
I got the Conti GP5000 and latex tubes mounted and my Nopinz road suit arrived.
Currently in in the last week of SusPB LV, but the weather was close to perfect so I decided to try out a 100km (60 mile) TT. Never done one this long before, so I paced it conservatively. My goal was to complete the 100km in under 3 hours.
Somehow my HR decoupling ended up negative 
Super happy I nailed it and well above goal pace. Picked up the power a bit in the last hour, but I didn’t fully empty the tank. Still need some energy to finish the last week of SusPB. Plenty room left to go faster. Ideally shooting for closer to 0.8 IF next time.
This result tells me the tires and suit help a ton! Extrapolating this to around the same effort as my 10 mile tt I’d expect to get over 37 kph average:
In general a 10% increase in speed requires a 23% increase in power. 192W x 1.23 = 236W which is just a couple watts below my 10 mile effort, would lead to a 34.2 x 1.1 = 37.6 kph (23.3mph). So @hvvelo, looks like you were about right in your predictions. Though I still need to put this into practise ofc. A proper TT helmet would probably also add some speed, but not gonna invest into that atm.