First of all you said you are raising T8 on the Turn as a default. I would not recommend to do so. Not only because your Callingrange gets too weak but with midpair and medium Kicker, you don't have an edge against his bettingrange and you don't have a good valuebet on the River against all his single Pairs Jx and better Tx and to strenghten your callingrange and for the simple fact that your Equity is not high enough, you should just call a hand like T9 or T8. Mostly you would have 3bet A9 and A8 Preflop so we can quite deduct these hands off your range. As well as a hand like KQ you'd certainly 3bet Preflop. So your callingrange on Flop and Turn is quite down to Tx and 7x combinations.
If we'd assume that your opponents knows that, we can simply figure out that folding all Tx combos would be really exploitable and a mistake. So with no Read you should Call any Tx Combo on the River. Lets check out your range, the chancerate how often your opponents bluff has to work out for him and then distribute your hands and see what you're supposed to be folding and how many hands you should be calling with.
It's also ok to just call a hand like J2 and J4 on the Turn, so i put these hands into your range. As Pocketpairs you might have 44 55 66 in your Turn-Callingrange but lets say 66 just 50% as you'd 3bet sometimes. A few pasively played Q9 Combos like 4. A6 A5 
sometimes.
55-44, 6h6s, 6h6c, 6s6c, QhTh, QsTs, QcTc, Th9h, Tc9c, Ks8s, Th8h, Ts8s, Tc8c, Kd7d, Kh7h, Kc7c, Qd7d, Qh7h, Qc7c, 9d7d, 9h7h, 9c7c, 8d7d, 8h7h, 8c7c, As6s, Th6h, Ts6s, Tc6c, 7d6d, 7h6h, 7c6c, As5s, Th5h, Ts5s, Tc5c, 7d5d, 7h5h, 7c5c, Jh4h, Js4s, Jc4c, Th4h, Ts4s, Tc4c, 7d4d, 7h4h, 7c4c, Jh2h, Js2s, Jc2c, Th2h, Ts2s, Tc2c, 7d2d, 7h2h, 7c2c, Kd9h, Kd9c, Kh9d, Kh9c, Ks9d, Ks9h, Ks9c, Kc9d, Kc9h, Kd7h, Kd7c, Kh7d, Kh7c, Ks7d,
That could be your range. 210 Combos, Card Removal included. Given 1:6 for your opponent, you should not fold more than 16,6% on the River.
Expressed in Combos you should not fold more than 35 Combos. But to be honest, i would fold all the 7x combos here and the weak Pocketpairs, though you should not, accordint to GTO. He should not be betting as light.
When you take out the weakest 7x combos like 75 76 etc, you have already 39 Combos deducted and still have K7 and Q7 included and if we exclude all 7x Combos and 44 55 66, we have just 138 Combos remaining but still weak hands like K9 and Q9 in.
A read would be necessary. Against tight and reasonable opponents who do not randomly bet on the Turn with A2 22 K3 and fire blindly through, i'd recommend to fold all the weak 7x and PP's by the River.
Suggestions?
