ELF sections and initialising thread-local storage on baremetal applications - embedded

Question

I am porting Musl libc for a baremetal project. Musl only targets ELF executables, so I have to "bootstrap" an ELF environment before handing control to __libc_start_main. The main data structure of interest is the system args/environment/auxiliary vectors. They can be mocked something like this:
long elf_vec[] = {
reinterpret_cast<long>("baremetal"),
0, // Argc/Argv
0, // Environment
AT_PAGESZ, 4096,
AT_UID, 1000,
AT_EUID, 1000,
AT_GID, 1000,
AT_EGID, 1000,
AT_SECURE, false
0, // Auxilliary vector
};
Musl also uses this information to initialise thread-local storage. By inspecting the ELF headers and extracting a TLS section, Musl will ensure that enough thread-local storage is allocated.
What I'm not sure how to do correctly is mock this in a bare-metal environment. To my knowledge, it's not possible to get the linker to directly embed the ELF headers into a program. I can't use an ELF library to extract the headers, as the Boot ROM contains a binary image. The approach I have tried is to create my own ELF headers:
Elf64_Phdr tls;
tls.p_vaddr = reinterpret_cast<Elf64_Addr>(&__tls_start); // linker variable to TLS region
tls.p_type = PT_TLS; // TLS header
tls.p_align = sizeof(uintptr_t);
tls.p_filesz = __tdata_end - __tls_start; // End of tdata region
tls.p_memsz = __tls_end - __tls_start; // End of tbss region
tls.p_offset = 0; // Invalid value
tls.p_flags = 0; // Invalid value
long elf_vec[] = {
/* ... */
AT_PHDR, reinterpret_cast<long>(&tls),
AT_PHNUM, 1,
AT_PHENT, sizeof(tls),
/* ... */
};
It "appears" to work, but I'm not confident in this solution without a lot of testing and auditing the code-base. Is this approach along the lines of what is required? Or am I over-looking a simpler solution to embedding ELF headers into a binary baremetal image?
Another option I've considered is using a second-stage bootloader that can perform ELF image loading, like U-Boot, although the target SoC does not have a vendor supported solution.