Looking into remote filters for my gen set this way u can get ones that are more available from a local parts house. Rather than ebay nos itmes.
The spin on oil filter and the drop in fuel filter cross over to auto parts that are available at low cost, under $10.00 each. The air filter was running on e-bay for $35 for three which is pretty good. The air filter system would be easy enough to modify by using radiator hose pieces and exhaust tubing and terminate with a K&N hose clamp style they sell for the small cars. However, the existing steel housing has the restriction gauge and is well baffled to limit noise. Also protects the filter from weather and has a dust ejector on the bottom. Best bet for an overall conversion might be to obtain a small automotive housing from a junkyard and adapt. It will be noisier.