I assume your playing 2-5?
In regards to the 3bets: fold to all of them [An argument could be made for calling w/ Q-T: it's not a great argument tho]. Getting 3bet after making an UTG raise is the ultimate sign of strength. 3bet ranges are already super tight in LLSNL, combine that with the fact that your range is supposed to be super tight and were usually looking at QQ-AA, AK.
General Advice
Static preflop ranges are perfectly fine for LLSNL, but the hands you open really should depend on table dynamics along w/ position. Paying attention to table dynamics can drastically increase your winrate, and allow you to put yourself in more profitable situations postflop
If I'm at a really nitty table I'll definitely open KJo utg, because I'm likely to get to the flop HU or 2-way (God I hate nits)
If I'm at a table w/ a bunch of aggro regs (shouldn't be here anyways), my utg raising range in FR is going to be super tight. Like [AKo, AQs+, 88+)
If I'm at a table of all passive fish (2-5 semi-frequently, 1/2 all the time). My range looks something like (ATs+, AJo+, KTs+, KJo+, JTs+, 22+)
It appears your playing at a common table. A few good regs and the rest are fish. Stay tight, play in position, cultivate your image, and reap profits. Don't worry about 4bet bluffing, and polarizing your range, and out-leveling your opponents.
Lastly, a good rule of thumb of when to call raises to strictly hit your hand is this.
Effective stacks need to be:
15x the raise size to setmine
25x the raise size to call with suited connectors (IP is much more favorable)
35x the raise size to call with gapped SC's