I wanted to move the propane tank further up towards the hitch end of the tongue, so I can later put on a box to hold the outdoor stuff.

First off, everything was stripped down, inspected, and surface rust removed:
Click to view attachment
Next, new angle iron was welded in for support:
Click to view attachment

Expanded metal grate was then cut to fit, and welded in:
Click to view attachment

A piece of angle iron was welded on top of the expanded metal to keep the propane tank from sliding backwards (ithe tank will be rubber strapped to the expanded metal):
Click to view attachment

Add a nice shiny black paint job:
Click to view attachment

and a brand spanking new side-handled wheel tongue jack:
Click to view attachment

Ain't that pretty, now? I now need to get busy and de-chalk and wax up the fiberglass!

Lookin' good Jackie Now that you're experienced, ya wanna come to Portland and clean up my Scamp's

It looks good.

But... is it good to have the tank weight up so close to the tug?

Only as it (and the added utility box) increase tongue weight. You may want to shift some weight back in the egg to compensate.