If the tires would fit on a common ebike hubmotor's spoke flange diameter with some room to spare, you could machine rim flanges that would bolt to the spoke flanges.
Might take some wrangling to get the valve stem thru, but 90-degree stems might be used for that, and some creative angling of the stem inside the tire.
Or go tubeless and build the stem into the flange like a car rim.
That would get you at least 1kw in each wheel with two motors, or use a hefty single motor and do however much you want in a single wheel.
Less wheelie problem with two driven wheels, though, especially if you can make a weight-distribution-sensor-driven throttle-divider, that basically takes your throttle input and tells each controller to power it's motor inversely proportionally to the weight distribution (so if a wheel lifts it provides less power to the other wheel and more to the lifting wheel), as well as sensing the traction each wheel has (so you don't spin out a tire).
I'm not exactly sure how that would work, but in theory it should keep you rubber-side-down.
JustinLE has probably already done work you could adapt from his skateboard builds.
FWIW, with that much modding, I'd just design and build one from scratch to do exactly what I wanted, without worrying about what surprises teh factory might've left me to find (especially mechanical ones).