I like idea #2! I was trying to get the tray out to take this picture and it was kinda tough to get it out, and then I realized that the branch I used is pushing on the two ends causing a bit of a skew in the squareness of the cage and putting pressure on two corners
I've been thinking about this tonight, if it was my cage I would mod it for two reasons, If it were to tip over the bird could be injured or escape (to be honest I can't believe they even sell it that way, nice cage but it has a design flaw)
If the branch is taking the cage out of square I would figure a way to mount the perch that does not do that, can't be good for the cage and over time it may
permanently skew the cage (or make the cage "loose")
Now that I see the tray seems to have a good "lip" under it I would remove the branch temporarily and
get the cage to "settle" square again, then put the tray back in and look at where the tray meets the lip, pick 4 of the black holes in the pic below that the tray seems to lay the flattest on, They should be the same sets of 2 (like either the 2 on both end lips, or the 2 on both side lips)
Once you have 4 of the same type picked out as the flattest (or easiest to drill from position) matching the corners of the tray I would get a drill with a 1/4 inch bit and drill through the tray and lip at the same time as follows:
First you would go to Home Depot and buy 4 of these 1/4 inch (1/4-20) Stainless steel Round-Head Machine Screws that are 1 inch long
(
Everbilt 1/4 in.-20 x 1 in. Phillips-Slotted Round-Head Machine Screws (2-Pack)-33241 at The Home Depot )
And 4 of these 1/4 inch (1/4-20) Stainless steel Wing Nuts
(
Everbilt 1/4-20 Stainless-Steel Coarse Wing Nut-32251 at The Home Depot )
Once you're sure you have the right hardware, take a drill with a 1/4 inch bit, put downward pressure on the tray
and make sure it is not going to move, then slowly drill through the tray and lip
at the same time (aluminum is very soft, if you go slow and straight with medium RPM it should go very easy)
MAKE SURE where you want to drill
on the tray will be on the
center of the lip below
(you wouldn't want to drill through the tray and "miss" the lip or only hit part of the lip)
Now here is the trick, after you drill the first hole, attach the bolt and wing nut in that hole to keep the tray and lip aligned (when you tighten the wing nut make sure the tray is as straight and square as you would want it to be when you are done the job) Now you do the next hole and then attach the next bolt and wing nut, then just repeat again 2 more times
When you are done you will have a cage that Chili can be left unattended in without fear of him getting out somehow, the cage will also be much stronger, and the good part is just remove the 4 screws and wing nuts to disassemble the cage
Do not attempt this unless you are good with a drill, and Very important :
get the cage to "settle" square before starting (make sure the whole cage seems squared nicely through the whole Process)
Hope this helps !
Joe
WO-HOOO!!!!! And Chili looks fantastic in it. 
