Here is what i get with binwalk of firmware i needed to edit:
binwalk TL-WR841Nv13_RU_0.9.1_4.16_up_boot[191015-rel65109].bin
DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------
82592 0x142A0 U-Boot version string, "U-Boot 1.1.3 (Oct 15 2019 - 17:55:20)"
132096 0x20400 LZMA compressed data, properties: 0x5D, dictionary size: 8388608 bytes, uncompressed size: 3286220 bytes
1442304 0x160200 Squashfs filesystem, little endian, version 4.0, compression:xz, size: 4544848 bytes, 685 inodes, blocksize: 131072 bytes, created: 2019-10-15 10:05:11
meaning that i have to skip 256 * 512 bytes?
so the code will be:
dd if=orig.bin of=stripped.bin skip=256 bs=512
but then the next question. I used STRIPPED version of V13 (tp_recovery(TL-WR841N(EU)_V13_STRIPPED).bin) firmware for my router that i grabbed from this thread and that works fine! And I checked for sure that the difference between the original EU firmware and stripped version is just 512 bytes, here is what i get with binwalk
binwalk TL-WR841Nv13_EU_0.9.1_4.16_up_boot[180119-rel65243].bin
DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------
82464 0x14220 U-Boot version string, "U-Boot 1.1.3 (Jan 19 2018 - 17:59:01)"
132096 0x20400 LZMA compressed data, properties: 0x5D, dictionary size: 8388608 bytes, uncompressed size: 3101556 bytes
1442304 0x160200 Squashfs filesystem, little endian, version 4.0, compression:xz, size: 3435831 bytes, 651 inodes, blocksize: 131072 bytes, created: 2018-01-19 10:07:34
so compare that with the stripped firmware I got from this thread
binwalk tp_recovery(TL-WR841N(EU)_V13_STRIPPED).bin
DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------
81952 0x14020 U-Boot version string, "U-Boot 1.1.3 (Jan 19 2018 - 17:59:01)"
131584 0x20200 LZMA compressed data, properties: 0x5D, dictionary size: 8388608 bytes, uncompressed size: 3101556 bytes
1441792 0x160000 Squashfs filesystem, little endian, version 4.0, compression:xz, size: 3435831 bytes, 651 inodes, blocksize: 131072 bytes, created: 2018-01-19 10:07:34
the stripped version is just without first 512 bytes from the beginning. Its not cut until LZMA compressed data as you said...