You're talking multiple failures and/or conditions, to wit -
Gear Down + Engine Failure + Critical obstacles.
Take away any one of those three components and you're still stuck with a multiple failure/condition situation, something that basic statistical analysis and regulations do not call for, and is probably surviveable.
The "positive rate of climb" requirement for a 2 engined aircraft with OEI in the first segment may at first sound alarming, but in reality is not. Most aircraft that I do performance work for have a 'gear down' climb decrement of the order of 0.9 to 1.0%.
Galaxy flyer speaks of 1.3% for one type (I'll bet a dollar it's a type like the DC9 where the Gear doors must open during retraction, thus increasing drag).
As a 2 engined aircraft must make a
MINIMUM Gross gradient in the 2nd segment of 2.4%, subtracting 1.0% still leaves a fairly healthy 1.4% gradient, not fantastic, but if there are no obstacles, you'll live to fly another day.
Most pilots observedly achieve close to Gross gradients during training.
Even if you wish to stick to the Triple 'failure' scenario, remember that probably at least 90% of Takeoffs are at less than performance limiting weight, which will significantly improve climb gradient.
From a 1.0% degradation, you only have to pick up an additional 0.2% gradient from the lighter weight to achieve the Net flight path, which will (just) ensure obstacle clearance.
The "odds" are very much in your favour.
Regards,
Old Smokey