generator tray

I have a 94 class c that the original generator was replaced by an off the shelf model. It was not working properly so I bought a WENN 4750 watt generator Dimensions are 26x17x17 . After the original one was dumped the owner built a tray that reaches 3" below the bottom of camper . Its just a steel tray recessed 3" that's mounted on side rails on both sides. It was bolted in so it wouldn't slide out . I need a sliding tray that will allow me to pull generator out and be able to fill it up with gas and let it stay out while running. Generator weighs 106 lbs. So I need one to support that weight. Does anyone know where I might be able to find one at a reasonable cost ? I have been looking and it seems as soon as you enter RV the price goes up 10 fold like my Mercedes does. The tray in it now is getting rusty and I would like to replace it. Anyone with pics/ plans I would like to see what you built if possible. My tray looks like this I_x_I . Generator fits where x is. the "I"s are side of tray upper Part that slides on lip on side of compartment . I appreciate any help you may have in terms of location of a slide or plans to build one. you may email me at unccgrad@live.com to send pics or plans
Thanks for any and all help