As you've discovered, once you are up in the 100MHz+ range, little is "simple".
When using discrete capacitors and inductors, you have to consider their parasitic complements. Even basic connecting elements such as traces have to have their characteristics carefully considered, because they too have capacitance, inductance, impedance and skin effects.
It can all be mastered (and there are lots of good texts on practical RF design), but whilst it is simple to model such filters with ideal components, the physical reality is much more complex...
At 80m/3.5MHz filters are still built with discrete components and ferrite cored inductors. (See this ARRL 80m design.)
This link shows the inside of a practical DIY 2m / 150MHz bandpass filter, with screw mount piston adjustable capacitors and hand formed air-cored inductors. The adjustable caps are critical, because you need to compensate for the hard to predict stray capacitances. The inductors are air cored due to high ferrite losses, and low target inductance.
Professionally designed/built filters in the GHz range will typically use transmission line designs created with CAD software which can do EM analysis. You will rarely see discrete components, just oddly bent traces and stubs, but they can work wonderfully.
Have a look here for an example of a 3GHz-11GHz bandpass filter from a master's thesis.
And the resulting performance.
In your case, you'd want to make sure you are using air cored inductors, and that you allow for stray/parasitic capacitances.
A discrete design built in a metal box like the 2m example, might be your best approach in terms of ability to experiment. In fact you could just adapt the example circuit for your use by tweaking the values