You will have an odour problem using urine. this is the ick factor I would be concerned about, not using urine which is a fine source of nitrogen diluted 1:10 but it stinks to high heaven and there's no getting around that. Undiluted, it certainly will burn young plants as well. \Think dog pee spots on the lawn as comparison.
I would go with your already sourced out free dried rabbit manure if it was my container garden.
If you do go with the urine, don't tell your dinner guests... although you might not have to tell them if they get a whif
I am wondering What have you got against composting? it's not difficult and doesn't take up much space.
For my containers (which are just large pots with no reservoir) I use 1/3 compost to 2/3 peat based potting soil and monthly applications of granular organic fertilizer which is blood and bone meal based. Works for me and nobody's allowed to pee on my mato's. Matter of fact I would probably kill anybody who tried.
KarenO