Sucks your ramp options are such extremes.
The extender lowers rating for sure. Agree you would only want to use at the launch and not for the 25 mile commute.
Another option (if the 2' doesn't get the job done) may be to have a trailer shop make a 8-10 foot extension you can clamp on when you launch. Could be pretty simple. You should be able to fit a 10' pipe in the van down the middle.
Or maybe something could be made to bolt in place of the swing away tongue for launching.