^^ Just to give you a heads up we don't SWIM here at Bluelight.
Everyone here realizes SWIM is you & it offers you no legal protection so please avoid using it here.
Besides that welcome to Bluelight & onto your question.
I don't believe sublingual is any better than oral but have not actually attempted to do so.
AFAIK there isn't really any reason it would be better than oral which is around 10% bio-availability.
Nasal is your best bet if you don't IV due to better bio-availability approx 43% if I recall correctly.
I don't IV & I don't enjoy nasal as I have had some sinus issues. (Deviated Septum fixed by Septoplasty)
I find a great way to reduce the damage from nasal admin is to just make a nasal spray.
A simplified example of the method I've used follows.
1. Take desired amount of Opana IR's and dissolve in appropriate amount of water or saline.
For example my spray bottle sprays .1CC's per spray.
So for example if I wanted .5mg per spray I would dissolve 10mg's into 2 CC's of saline.
That would make it 5mg's per CC, or .5mg per .1CC spray.
2. Once dissolved I cotton filter the solution.
3. Repeat step 2 and filter again.
4. Put solution in empty nasal spray bottle.
I use a pump spray for example a generic for Afrin No Drip.
5. Administer spray & experience breakthrough pain relief or get high whatever's your pleasure.
6. Repeat step 5 till your good to go.
The above method works great for me I hope it works as well for you if you choose to use it.
Though it doesn't eliminate all the irritation from nasal admin it definitely helps.
Even better would be micron filtering rather than cotton filtering but not everyone (myself included) has access to them.
If you do happen to find another method besides nasal admin that works well I'd be interested to see information regarding it.