It's all about AoA control. Speed is much less relevent. If you control AoA to give you momentarily zero G, speed will hardly matter at all for that moment, If your AoA has you pulling 2G, you'd better have extra speed. This should be entirely a feel and sense thing for a competent pilot. Reading instrument information should be extremely secondary.
Trimming a plane is a nice thing to do once extablished in a configuration. Trimming is near the least important thing you could attend to during a forced approach, unless you're gliding down from a few thousand feet.
"Best glide speed" and "best climb speed" can be traps. If you're in a vulnerable phase of flight, and you can, add 5 to 10 knots to each of these speeds, and expect the lesser performance, it'll keep you more safe. Inertia is your friend, when you must flare.
There was talk of retracting flaps for a glidepath change. No. The first setting or two of flap extension on most GA aircraft is a lift increase, so you can fly more slowly, more will be drag, but still some lift. You do not want to give up that lift, particularly if you are flying the slower flaps extended approach speed. Once down, either stay down, or apply power and overshoot - so for a forced approach = flap stay down.
'One of the several reasons I like slipping. Side or forward slip distinction is less vital than just precisely cross controlling, and getting it where it needs to be in the correct speed range. I like to slip, until the landing zone is assured, then exend the flaps as needed for a slightly fast approach.
If you reach the flare with too much inertia, use full flaps, and slip off as much as you can. You can touch down fully slipped if you need to on many GA types. It may be lumpy, but better than under/overshoot.
The use of a slip for glidepath control is a bit of a crutch, which some pilots will criticize, but it did mean that your approach have more opportunity to glide to a safe touch down than a plain glide approach.