1.35 is plenty strong enough on a 1.35 tarp. It's more a matter of how they are attached and size.
Size- about a 3-5" distance fron the corner is fine on a small to med size tarp. (half of a 6-7 suare will end up as a 4" after rolling the edges into the hem.)
For ultimate strength, bond them to the tarp with a very light coating of silnet/silicone, let dry, before rolling the edge hems. (We use a special double sided permanent tape instead of silicone-don't ask- none to sell...)
Wider perimeter hems (more than 1/4", 1/2 to 1 is good) are srtonger.
Roll the reinforcement into the edge hem as you make the hem and then stitch the reinforcement(across the hypotenuse of the triangle) with a med to wide stitch spacing about 1/4" from the edge of the tarp on the reinforcement. The stitching is more to prevent bond failure than attaching tarp to reinforcement.
If you really want to go all out, add another line or two of stitching mid way through the reinforcement perpendicular to the hypotenuse.
A key DYI pitfall is setting stitch spacing too tight or to bartack/zigzag a tieout on too tight as that put too many stitches too close together and thus make a rip-along-the-dots possibility. Try wider space dual bartacks rather than one beefiers one. The pretty big beefier ones are best for heavier fabrics.
On many smaller tarps, you can do without the reinforcements all together (at least everwhere but the corners and maybe ridgeline) if you use wider hem and double stitch (two rows) the hem. The width of the hem spreads the tear force over a wider area very well. Just keep the tieous near the tarp edge so the force falls on the bartack and then the two rows of hem stitching. I've never had one tear out made this way and it saves a bit of weight.