Weight, Clamp or stabilizer?

7/8" is ample for most clamps (are you allowing for thickness of the mat?) IMO, a real clamp is the way to go — some are very light, very inexpensive and very effective.

I don’t understand using a weight. I have a massive one, 800 grams, and it can’t flatten even a slightly warped LP — whereas a clamp, exerting active pressure (and weighing 90% less) does a far better job. And you are right to consider the load on the bearing.

You are "willing to tweak", and once you have the clamp, there are some very neat tricks to flatten the record totally: full contact with the platter right out to the edge. These tweaks are not expensive, and readily available: only two small parts. They require a bit of DIY but well within the skills of even a modest handyman, with basic tools.

And it really works. You’ll see and hear the improvement.

I don’t know if I’m allowed to recommend one here. If so, I will. Otherwise, you needn’t spend much, as long as the clamp has a collet. When you get it, I’ll be happy to elaborate on the tweaks, or send you links to a simple how-to.

Let us know.

New mat, definitely.  Rubber ages even if it seems new.  Don't try to fix a warped record with a weight or clamp unless its the only copy...there are plenty of either new presses or 'good' copies at some price point.  A wobbly record will wear unevenly and depending on your pitch sensitivity will drive you crazy.

Change the needle/cartridge to something about $150.

Buy new MFSL anti-static original master sleeves and keep the paper ones as nostalgia.

Buy a motorized, liquid washing system, approx $200-$500.  I have found this is the best way to clean but also remove static before playing.

I'm trying to get it to produce the best sound its capable of. I plan to order a set of SVS subwoofer feet to replace the worn feet .... I read an article about TT tweaks. A few things they suggested were an upgraded mat, clamp and isolation feet.

The best you can do at the first step is to upgrade the cartridge!

This is by far the most important. You can do all the tricks, but without a decent cartridge in contact with your vinyl grooves all upgrades makes almost no sense. Make sure you have the right cartridge first. Some vintage MM cartridges are great, Pioneer PC-1000 mkII was their best cartridge (absolutely amazing, look at the package).  

A good cartridge will change the sound of your system even on felt mat without clamp or weight. 

All the tricks such as mat, clamp will make some improvement, but not as huge as the cartridge. 

BTW Pioneer dist stabilizer is very nice. Micro is another top-notch stabilizer. As for the Mat i would recommend SAEC SS-300

Adding a heavy clamp is not a good thing on the pivot bearing, rather a clamp from Michell that weighs little and is cheap, but has a chuck like that of drills to grind and allows the disc to be fixed firmly to the mat.