Custom steel balancebike for my Kid

Most tricky werw the specialized carbon wheels. The wheelset is designed for theire carbon hotwalk that comes with airless tires. For whatever reason the wheels are available as a replacement part but not the tires. Therefore I have to combine the wheels with tires and tubes but do the rims have a valveholes? Other problem is the 110mm hubspacing. The balance bike standard is 95mm but these are 110mm wide. 110mm balance bike forks are impossible to get and for futureproof reasons I didn't want to build the rear 110mm wide. Seems like the easiest solution is to shorten the endcaps by 9.5mm on each side. 110mm-(2x9.5mm)+4mm(2mm washer on each side)=95mm. The other problem it the use of an 8mm proprietary axle instead of usual 5mm qr. The thread of the 8mm axle is to short to fit 95mm spacing. I decided to use a stainless M8 thread-bar and do kind of a bmx/track hub conversion with a floating axle. To save the ankles and other kids and adults flesh I went for safe and reasonable round dome head nuts even if I would have preferred to use the fancy but sharp edged titanium bi-hex nuts or even the drilled racing ones. Seat post diameter is even a mess on balance bike. The lack of standards in the bicycle industry is shocking. From 22,2 to 25.4mm you can find everything so I went for the 27.2mm most common adult size. The saddle is a pivotal bmx race seat because the pivotal system stay much lower than classic rail saddle models. The stem is a 25mm short Intend Grace DD. It is CNC machined in Germany with integrated topcap and no sharp edges to save the chest area and face in the worst case of a frontal collision with this brakeless rocket.