Slide Tray under ute ... & tyre carriers

Sorry if yeah getting sick of my questions but figure this is the place with the knowledge.

I have a rodeo single cab ute ...... I am looking at placing a sliding tray under my tray ... which will give approx 1800 x 850 x 180 high with will slide out to give (guessing 1500). I want to use this space for tools recovery gear etc etc etc) with the top to be used as a cooking top or what ever.

Does anyone have something similar or what are the pro's and con's of this?

Next.

Tyre carriers I have my tyre secured behind the passenger seat in the tray was toying with the idea off something like the Kaymar carriers external of the tray as i'm looking at a 2nd tyre, doing this allows me to sleep in the back if I want. The rest of the space will be taken up with fridge stove shelfs etc etc.

Pro's and Con's again.

I must admit the weight on the rear is a concern to me, would this be a major issue?

Thanks
Brian