Good work so far. Go for stowage on top of the bus,
it will look great. I would paint the widows (several guides
on how to get good looks for it on LAF) It has the advantage
of removing the need to do interior details like drivers. I am
like you & reluctant to use power tools to take toys apart. I
manage to injure myself enough with non power tools as is.

Especially this time of year (Halloween is coming) keep your
eyes open for cheap (Poundland etc) table covers. The scary
images might suit Gaslands better that the existing table tops.
Or a visit to Dunhelms, where they sell leatherette material by
the metre. In the range is a nice (muddy) brown. Much cheaper
than commercial battle mats. If you want you can easily make
a race track by soaking a sponge with a lighter brown & just
dragging it around the leatherette.
Keep up the good work, & keep it fun.